2006/2007 Mac Pro (1,1/2,1) and OS X El Capitan

[rthpjm]

If you haven't already, try using the following steps found in this video:

I installed El Capitan using the method above and it works perfectly fine with a new GPU added to it.

Let me know if it works

That procedure works. It is an excellent walk through of the basic steps to replace the two efi files. It does however have a few drawbacks in my mind:

1. The creator of the video tutorial distributes a disk image file from an already installed system.
   • I have not checked recently, but I believe it is against Apple's license to distribute a copy of MacOS as a source for installation. (These things are likely a sliding scale, but we do know that Apple occasionally enforces its will through cease and desist orders).
   • I always worry that such a DMG is an unknown quantity. It may or may not be a potential source of malware. In this case it is almost certainly NOT infected, since lots of people have used this method.
2. This method does not create a usable Recovery HD partition.
   • The steps to achieve a usable Recovery HD partition are available. A search should turn them up.
   • It's an extra set of steps that are not addressed by the video creator.

The Pikify method(s) on the other hand address the above issues, although Pikify does introduce its own constraints:

1. Use the Apple distributed installer as the source.
   • To my mind this is a much "safer" approach, and during the life-cycle of El Capitan meant that the start point could always be the most recent "point release" from Apple (10.11.0, 10.11.1, ... 10.11.6)
   • Some people struggled to download a copy of Apple's installer, but thankfully Apple produced an article and a download link that helps.
2. Pikify correctly installs the main OS partition AND installs the Recovery HD partition correctly.
3. The constraint is that the MacPro must have 12GB of RAM (or more)
   • The RAM requirement is a side effect of the method, which uses the Apple Install Assistant in a immutable mode (not writable). It assumes the use of non-writable media such as a DVD. Apple's IA therefore creates some RAM-disks and copies the installer code to those before it starts. Mid way through the installation progress it must unarchive a large file. Because it is using RAM-disks, there must be enough RAM for it to successfully unarchive the large file, if not it crashes.

I am biased of course...

Choose whatever method works for you...

 

[jbarley]

I am biased of course...
Choose whatever method works for you...

And well you should be, thank you for everything you've contributed to keeping my old MacPro alive and productive.

 

[jabbo5150]

So I am wanting to put El Capitan on my Mac Pro 1,1.

I currently have 8 GB of RAM, so that would need to be at least 12, right? OWC has 32 GB for $229. Is that overkill or should I get that much?

I have 4, 1TB hard drives in my Mac Pro. Is the largest you can install 2TB? Should I do a solid state system drive? I'd need an adapter then, right?

I have the Radeon 5770 video card.

My Late 2011 Macbook Pro has Sierra on it, but I still have the Install El Capitan installer in the applications folder on that machine. I also have a USB installer that I created. Which way is the best (and easiest) to install on the Mac Pro? I have seen Target Mode but have also seen putting the installer in the applications folder on the Mac Pro.

From what I am reading, I wouldn't be able to download updates to the OS without making it unbootable, right? What about other apps from the app store? Will it treat my mac as an El Capitan machine and allow me to download accordingly? Same thing with 3rd party apps.

Anything else I need to know? I am excited about getting more life out of this machine. God knows running Lion is tedious at best in this day and age.

Thanks in advance

 

[rthpjm]

So I am wanting to put El Capitan on my Mac Pro 1,1.

I currently have 8 GB of RAM, so that would need to be at least 12, right? OWC has 32 GB for $229. Is that overkill or should I get that much?

I have 4, 1TB hard drives in my Mac Pro. Is the largest you can install 2TB? Should I do a solid state system drive? I'd need an adapter then, right?

I have the Radeon 5770 video card.

My Late 2011 Macbook Pro has Sierra on it, but I still have the Install El Capitan installer in the applications folder on that machine. I also have a USB installer that I created. Which way is the best (and easiest) to install on the Mac Pro? I have seen Target Mode but have also seen putting the installer in the applications folder on the Mac Pro.

From what I am reading, I wouldn't be able to download updates to the OS without making it unbootable, right? What about other apps from the app store? Will it treat my mac as an El Capitan machine and allow me to download accordingly? Same thing with 3rd party apps.

Anything else I need to know? I am excited about getting more life out of this machine. God knows running Lion is tedious at best in this day and age.

Thanks in advance

Hello jabbo5150, welcome to "keep the first edition MacPros running club"

If you read post #1 of this thread you will see that there are 2 main approaches.

1. Hook your disk up to a supported Mac, perform a straight forward install, then manually replace a few files before attempting to use the new installation with the MacPro.
2. Start with the MacPro running an older version of Mac OS X, perform a "modified" installation directly.

If you choose approach (1), you can put your MacPro into "target disk mode" and attach it to a suitable newer/supported Mac, or physically remove a drive from the classic MacPro and connect it to the newer/supported Mac directly or with a caddy/adaptor. Remember that this method needs you to manually modify the main OS partition (replace the two boot.efi files), and if you want full usability then you also need to modify the (hidden) Recovery HD partition too.

If you choose approach (2), then the OS and the RHD are prepared for you (if you use the pikify script or app). During the install procedure, the method requires 12Gb RAM during the install phase (see my description of why a couple of posts back). Once the installation is complete, the 12GB requirement can be relaxed - but unless you "borrow some RAM" I would always recommend keeping/using as much RAM as possible with El Capitan, you get better perform all around with more RAM. So yes, buy more RAM if you can afford some, I personally think you will benefit with 32GB for the install AND for the future lifetime of your classic MacPro.

Let's address the update issue. These original Mac Pros shipped with 32-bit EFI firmware (the newer equivalent to legacy BIOS firmware). By the third iteration of the Mac Pro (2008 aka 3,1), the industry had released a 64-bit version of EFI, which Apple promptly adopted. When a Mac Pro boots, the machine uses the Firmware EFI to "cold bootstrap" the system. The firmware has a minimum set of "drivers" allowing it to interact with hardware and the file system. It is "aided" by an on-disk file containing more device specific EFI code. This is the boot.efi file that we talk about. This on disk EFI code allows Apple to extend the EFI boot sequence without needing to resort to a firmware update. The boot.efi file performs the majority of the late stages of the boot sequence before handing over control to the Mac OS X kernel.

When Apple officially stopped supporting the classic Mac Pro 1,1 and 2,1 way back with Mountain Lion 10.8, it meant that the on-disk boot.efi file could drop support for the 32-bit EFI firmware. It's a double whammy for the cMP, it's not officially supported and it now won't boot because the on disk boot.efi file is expecting 64-bit function calls into the EFI firmware. A community contributor known as tiamo originally provided a modified boot.efi file that "thunks" the expected 64-bit function calls and effectively rewrites them to be compatible with the 32-bit firmware. Tiamo stopped contributing for a while, at which point another contributor known as Pike R Alpha (often referred to as pike or piker) took up the work and continued to adapt the boot.efi file making it compatible with changes coming from Apple as Mac OS X continued its release cycles.

Now, when Apple releases updates to Mac OS, sometimes (but not always) those updates contain a new version of the boot.efi file. This is "bad" for us because when the update replaces the community modified boot.efi file we are back to being "unbootable" for the reasons outlined above. The solution is to simply "put back" our community modified boot.efi file. In the words of Douglas Adams "DON'T PANIC". It's simple. Boot the MacPro from another partition (such as the Recovery HD - see above), and copy the community boot.efi file into the two locations. (It has never been the case that an Apple boot.efi file is installed on both the main OS partition and on the Recovery HD partition at the same time). Or use Target Disk mode, or a caddy/adapter with another Mac copy from there.

The community also came up with a solution that "watches" the two boot.efi file locations. It detects when a boot.efi file is overwritten and automatically puts the community version back. There were lots of contributors working on parallel solutions for this (including myself), there are two often used solutions known as capitanpikefix and Boot64, they both do effectively the same thing.

Having said all of that, if you start your upgrade using Apple's latest point release 10.11.6, then there is very little to be worried about. Mac OS has moved on to Sierra and High Sierra. El Capitan will likely see one or two more security updates but it is highly unlikely to receive a 10.11.7 update. Apple has never shipped an updated boot.efi file with a security update (to my knowledge). The use of capitanpikefix or Boot64 is probably optional now once you are up to date with 10.11.6...

The modifications we've been talking about are there simply to restore the cMP ability to boot. Up to and including El Capitan that was all that was required. Once booted the cMP could run Mac OS X natively with no further modifications (not true for other unsupported platforms based on the mobile motherboards including minis, 'books, and iMacs). The classic MacPro hardware was (and still is) a highly capable 64-bit Xeon workstation-class machine. You can upgrade a 1,1 with newer CPUs effectively turning it into a 2,1. You can also upgrade the wifi/Bluetooth combo card to give you newer features enabling support for handoff etc... However, there comes a time when all good things come to an end, that time was Mac OS Sierra 10.12.x. At this point we find that Apple (quite rightly) is making use of hardware features that the classic MacPros simply do not have, e.g. Low-level hardware features of the newer Intel CPU families.

For compatibility, if software declares support for El Capitan (and doesn't break any development rules), then it should/will run fine on a Classic MacPro. Be cautious of software that makes use of other hardware (audio and video software comes to mind) our classic MacPros may not have the hardware that the software is "expecting". Other than that, it is my experience that everything (I choose to use) works flawlessly.

We should congratulate Apple and the third party software houses for a great job. The fact that we've been able to keep unsupported MacPros running for so long is astonishing and for me gratifying. It has allowed me to declare that my original purchase of a MacPro 1,1 was the best purchasing decision of my technological life. I am waiting expectantly for the 2018 MacPro to emerge.....

 

[jabbo5150]

Hello jabbo5150, welcome to "keep the first edition MacPros running club"

If you read post #1 of this thread you will see that there are 2 main approaches.

1. Hook your disk up to a supported Mac, perform a straight forward install, then manually replace a few files before attempting to use the new installation with the MacPro.
2. Start with the MacPro running an older version of Mac OS X, perform a "modified" installation directly.

If you choose approach (1), you can put your MacPro into "target disk mode" and attach it to a suitable newer/supported Mac, or physically remove a drive from the classic MacPro and connect it to the newer/supported Mac directly or with a caddy/adaptor. Remember that this method needs you to manually modify the main OS partition (replace the two boot.efi files), and if you want full usability then you also need to modify the (hidden) Recovery HD partition too.

Thanks for the help!

What about this link, which I found via Mac Rumors:

Seems I can download that to my Late 2011 MacBook Pro and attach it to my Mac Pro 1,1 and install in target disk mode?

I have never done target disk mode, so what all would I need to do to make that work? Am I oversimplifying things or is that all I would need?

I do have a working El Capitan installer already on my MacBook Pro, though I don't know if it is the most recent version or if it would have to download updates.

Also, I want to upgrade the hard drives on the Mac Pro 1,1. I currently have 4, 1TB drives in it and would like to go to 2TB each. I am seeing conflicting things about drives larger than 2TB not being very compatible for the Mac Pro. Is WD Black still the way to go or is there something comparable that won't cost me $130 a drive?

I plan on ordering memory upgrades today. Thanks again!
[doublepost=1506275621][/doublepost]One other question. If I do install using target disk mode, would I be able to install over my existing Lion system as an upgrade or would it have to be a fresh, clean install? If I installed El Capitan on my Macintosh HD disk, would it have two OS's on that disk or would it know to update Lion?

 

[rthpjm]

Thanks for the help!

What about this link, which I found via Mac Rumors:

Seems I can download that to my Late 2011 MacBook Pro and attach it to my Mac Pro 1,1 and install in target disk mode?

I have never done target disk mode, so what all would I need to do to make that work? Am I oversimplifying things or is that all I would need?

I do have a working El Capitan installer already on my MacBook Pro, though I don't know if it is the most recent version or if it would have to download updates.

Also, I want to upgrade the hard drives on the Mac Pro 1,1. I currently have 4, 1TB drives in it and would like to go to 2TB each. I am seeing conflicting things about drives larger than 2TB not being very compatible for the Mac Pro. Is WD Black still the way to go or is there something comparable that won't cost me $130 a drive?

I plan on ordering memory upgrades today. Thanks again!
[doublepost=1506275621][/doublepost]One other question. If I do install using target disk mode, would I be able to install over my existing Lion system as an upgrade or would it have to be a fresh, clean install? If I installed El Capitan on my Macintosh HD disk, would it have two OS's on that disk or would it know to update Lion?

Hello jabbo5150,

Let's set a few things straight before we go much further. There is a difference between "installing" and "disk cloning".

The Pikify method is a modified installer. It performs a "slipstreamed" proper installation using Apple's installer tools. It's been extended to "slipstream" the community modifications into the install sequence.

The YouTube links you are referring to are using disk cloning. That is an already built system, then a clone is made into a disk image. If you're familiar with the PC world, it's the equivalent of an ISO disk image.

In your postscript you ask if you can use the YouTube methods to install over your existing Lion system. In the context that you pitch the question (upgrade in-place) the answer is no. A disk image is "restored" to the target disk and will therefore overwrite anything on the target disk. You can start with another disk (not your Lion one), restore the image, boot from the new El Capitan disk, then run the Apple Migration Assistant (found in Applications:Utilities), use the Lion disk as the source when prompted.

I repeat that I personally don't like using a disk image. It's my personal preference. If you want to perform an in-place upgrade, then you need to use the Apple installer tools.

You can use a newer supported Mac to do this, then manually replace the required files, or you can use Pikify to perform the install directly on your MacPro.

I don't know what you've been reading about disks and the MacPro!!!
I've got 3Tb hybrid drives, and 4Tb regular drives installed. There's no reason to worry about drives and sizes to my knowledge. Certain disk "formats" won't necessarily go much higher than 2Tb, (DOS-based FAT springs to mind, it is so old that the authors of the standard never guessed that we would be at 32-bit operation systems and applications, never mind 64-bit!). Thankfully, the hardware doesn't really have an impact on the format you choose. HFS+ has been 64-bit compliant for a very long time. Have a look at Wikipedia for the sizes supported by 64-bit formats (from memory it's in the petabyte region if not more).
So long as the drive has SATA I/II (or backwards compatible III) listed, then the MacPro will be fine.
Brands have varying reliability, I've had some 3Tb regular drives from one particular manufacturer that all failed after around 12 months. Thankfully a different brand/model of 4Tb disks has been much more reliable for me.

Read this Apple article about Target Disk mode https://support.apple.com/en-gb/HT201462

You need the same interface at "both machines", typically this means FireWire 800 because that's the fastest interface on the original MacPro. I think the 2011 MBP has FireWire 800. You just need a cable....

In summary:

• Using Target Disk mode you have two choices
  1. Use the MBP to run the unmodified 'Install OS X El Capitan' application found in the Applications folder of the MBP. When asked select the FireWire mounted volume from your MacPro. Let the install complete, but do not try to boot into then new El Capitan volume yet. You must manually copy the "Pike" boot.efi files into the two locations on the FireWire mounted volume that's just been installed. (search for the step-by-step instructions)
  2. Use the MBP to "restore" the disk image from one of the YouTube links. Remember this is destructive, so use a different volume or make sure you have a good backup of your Lion data.
• Using the MacPro only
  • Make sure you have 12GB of RAM or more
  • Put a copy of Apple's unmodified 'Install OS X El Capitan' into the Applications folder of the MacPro
  • Download the Pikify v.14 script (and supporting files), or the new app
  • Run the createpikeinstallmedia script (watch the video), or run the App.

 

[jabbo5150]

Hello jabbo5150,



In summary:

• Using Target Disk mode you have two choices
  1. Use the MBP to run the unmodified 'Install OS X El Capitan' application found in the Applications folder of the MBP. When asked select the FireWire mounted volume from your MacPro. Let the install complete, but do not try to boot into then new El Capitan volume yet. You must manually copy the "Pike" boot.efi files into the two locations on the FireWire mounted volume that's just been installed. (search for the step-by-step instructions)
  2. Use the MBP to "restore" the disk image from one of the YouTube links. Remember this is destructive, so use a different volume or make sure you have a good backup of your Lion data.
• Using the MacPro only
  • Make sure you have 12GB of RAM or more
  • Put a copy of Apple's unmodified 'Install OS X El Capitan' into the Applications folder of the MacPro
  • Download the Pikify v.14 script (and supporting files), or the new app
  • Run the createpikeinstallmedia script (watch the video), or run the App.

Good to know regarding the hard drives.

So if I use Target disk mode, can method one above be used to install over my Lion disk or are both methods destructive and needing a different volume?

Same question as above if I use the pikify script. Is it a destructive process?

Thanks again
[doublepost=1506338321][/doublepost]Also, is there a way to tell if the El Capitan installer I have is the most recent one (10.11.6?)? It may be as I installed it on my MBP well after its release. Or should I redownload it from the app store to be sure (If that is possible)? It is still in the applications folder of my MBP.

 

[rthpjm]

Good to know regarding the hard drives.

So if I use Target disk mode, can method one above be used to install over my Lion disk or are both methods destructive and needing a different volume?

Same question as above if I use the pikify script. Is it a destructive process?

Thanks again
[doublepost=1506338321][/doublepost]Also, is there a way to tell if the El Capitan installer I have is the most recent one (10.11.6?)? It may be as I installed it on my MBP well after its release. Or should I redownload it from the app store to be sure (If that is possible)? It is still in the applications folder of my MBP.

I would redownload from the App Store personally. That way you will be starting with 10.11.6.
You will need to remove ALL copies of the previous 'Install OS X El Capitan' from the visible disks. If Spotlight can "see" any copy, the App Store App will refuse to download another copy. (Actually it lets you click the download button, starts the busy spinner for feedback,..... then sits there doing nothing! Not very Apple-like!)

It's hard to tell what version you currently have, the version info is typically displayed for the App, not the version of Mac OS it will install... You can find out but it's not easy (unless someone else knows better?...)

Only the disk image restore methods are necessarily destructive.
Target disk mode (1), should allow an in-place upgrade.
Pikify (script or App), should allow an in-place upgrade.

I would always advise using a different disk/volume than your current active (Lion) volume, then use Migration Assistant. It's safer.
If you go for an in-place install, just make sure you have an off-line backup in case things don't go as expected...

Be brave and go for it!...

 

[jabbo5150]

I would redownload from the App Store personally. That way you will be starting with 10.11.6.
You will need to remove ALL copies of the previous 'Install OS X El Capitan' from the visible disks. If Spotlight can "see" any copy, the App Store App will refuse to download another copy.

Only the disk image restore methods are necessarily destructive.
Target disk mode (1), should allow an in-place upgrade.
Pikify (script or App), should allow an in-place upgrade.

I would always advise using a different disk/volume than your current active (Lion) volume, then use Migration Assistant. It's safer.
If you go for an in-place install, just make sure you have an off-line backup in case things don't go as expected...

Be brave and go for it!...

I do have a backup, so that is taken care of. I have never used migration assistant. If I remove that El capitan installer from my MBP, it should show up in my purchased area in the app store?

is there a benefit to using the Pikify Script over the app or doesn't it matter?

I am ordering my memory upgrades today. I want to upgrade my hard drives. the 4, 1TB drives are not enough space for me. if I went with an SSD for the boot drive, would I need to use trim? I have never had a SSD in any of my computers.

 

[rthpjm]

I do have a backup, so that is taken care of. I have never used migration assistant. If I remove that El capitan installer from my MBP, it should show up in my purchased area in the app store?

is there a benefit to using the Pikify Script over the app or doesn't it matter?

I am ordering my memory upgrades today. I want to upgrade my hard drives. the 4, 1TB drives are not enough space for me. if I went with an SSD for the boot drive, would I need to use trim? I have never had a SSD in any of my computers.

Install OS X El Capitan will show in the Purchased tab regardless (assuming you've previously downloaded a copy for your MBP or other Mac), you just can't download a fresh copy successfully until you remove the older copy/copies.

The App is effectively a GUI based on the same steps as the script (they are fundamentally equivalent)

TRIM is optional, but if it's available you should use it on an SSD. TRIM is a part of the process that tries to minimise degradation of the memory cells by reducing the read-erase-write duty cycles during normal operations.

 

[jabbo5150]

Install OS X El Capitan will show in the Purchased tab regardless (assuming you've previously downloaded a copy for your MBP or other Mac), you just can't download a fresh copy successfully until you remove the older copy/copies.

The App is effectively a GUI based on the same steps as the script (they are fundamentally equivalent)

TRIM is optional, but if it's available you should use it on an SSD. TRIM is a part of the process that tries to minimise degradation of the memory cells by reducing the read-erase-write duty cycles during normal operations.

Memory arrived today and I have installed it. I may try and do the OS tomorrow. If I went the SSD route, is TRIM something in the OS or would I need a separate program to do it?

I am wondering if I should move my home folder off of the boot drive too? I have never done this, though I have kept my iTunes folder on a separate drive

 

[rthpjm]

Memory arrived today and I have installed it. I may try and do the OS tomorrow. If I went the SSD route, is TRIM something in the OS or would I need a separate program to do it?

I am wondering if I should move my home folder off of the boot drive too? I have never done this, though I have kept my iTunes folder on a separate drive

Apple added a command trimforce to enable TRIM support for third party SSDs. (Look it up)

I can't help you with the other questions

 

[jabbo5150]

Apple added a command trimforce to enable TRIM support for third party SSDs. (Look it up)

I can't help you with the other questions

Thanks for the info.

So My MMP is running Sierra. I deleted the Install OS X El Capitan installer that I had in my applications folder and I see the link in my purchased tab. Next to it it says install. When I click on that, it does nothing. Is there another location I need to delete the el capitan installer to make it download again? Can I not download it because I am running a newer OS?

 

[jbarley]

Try this direct link...
https://itunes.apple.com/app/os-x-el-capitan/id1147835434?mt=12

 

[jabbo5150]

It is giving me this message:

OS X can’t be installed on “Macintosh HD” because the version of macOS is too new.
[doublepost=1506580204][/doublepost]I figured it out I think. I clocked on the OS X logo and it changed the install link to a download link. Then it asked if I am sure I want to download and I clicked yes. I think it is downloading now

 

[jbarley]

I figured it out I think. I clocked on the OS X logo and it changed the install link to a download link. Then it asked if I am sure I want to download and I clicked yes. I think it is downloading now

So did you manage to get El Capitan installed?

 

[jabbo5150]

Haven't tried yet. Probably tonight or tomorrow. I upgraded the memory and have some new hard drives I want to put in.. I am going to use the Pikify script or app way I think. Seems the most foolproof for me

 

[camacho]

I've been running El Cap on my Mac Pro 1,1 for awhile now although I had some issues with lag using PC version HD 6770's. I recently bought an Apple HD 5770 and I'm seeing the same type of lag. I have the dual 3GHz, 20GB RAM, SATA drives that all check out okay, and an Apple HD 5770. Sometimes it struggles to even open Microsoft Word and Chrome lags when I'm moving tabs or the window to my other screen.

Anything I could check to remedy the issue? Would a fresh install do anything?

 

[jabbo5150]

Another question from me. I am going to maybe try doing this install this weekend. When it asks me to contact Apple and submit my registration information for El Capitan, I assume I should not do that since it is not supported. Or doesn't it matter?

 

[Niccador]

Getting ready to install El Capitan on my 1,1 in the next couple days. (Well, 2,1 after I update the firmware.)
My current primary drive with Lion on it is a 750GB, which I was debating repartitioning into two 320ish partitions and installing EC on the new partition. (Keeping Lion available when/if needed.)

Is this possible, or even wise? Or am I better off installing to a separate physical drive?

EDIT:
And as long as I'm here...
I realize that El Capitan needs a beefier video card, and I've got a 5770 waiting to install once my power cable arrives.
In the meantime, am I still able to proceed with the initial installation with the current 7300GT, just to get it out of the way?

 

[jbarley]

And as long as I'm here...
I realize that El Capitan needs a beefier video card, and I've got a 5770 waiting to install once my power cable arrives.
In the meantime, am I still able to proceed with the initial installation with the current 7300GT, just to get it out of the way?

El Cap will install with the 7300GT but you'll not like how it runs.
For whatever reason EL Cap only finds and uses aprox 700KB of video memory.
And yes that is kilobytes...

 

[alpha1r]

I recently installed El Capitan on my Mac Pro 1,1 using Pikify v14.

I have 16GB Ram, an Apple Radeon 5770 graphics card and upgraded X5355 Processors. The install process went very smoothly, but I did notice that my Mac Pro would randomly restart, and than restart immediately again during boot up before it loads.

Going to try and zap my PRAM but just wanted to see if there is anything else I can do.

Thanks!

 

[owbp]

I recently installed El Capitan on my Mac Pro 1,1 using Pikify v14.

I have 16GB Ram, an Apple Radeon 5770 graphics card and upgraded X5355 Processors. The install process went very smoothly, but I did notice that my Mac Pro would randomly restart, and than restart immediately again during boot up before it loads.

Going to try and zap my PRAM but just wanted to see if there is anything else I can do.

Thanks!

El Capitan was more solid on my 1,1 than it was on my 4,1.
What does Console says after those reboots?

 

[rthpjm]

I recently installed El Capitan on my Mac Pro 1,1 using Pikify v14.

I have 16GB Ram, an Apple Radeon 5770 graphics card and upgraded X5355 Processors. The install process went very smoothly, but I did notice that my Mac Pro would randomly restart, and than restart immediately again during boot up before it loads.

Going to try and zap my PRAM but just wanted to see if there is anything else I can do.

Thanks!

Do you have any 512MB RAM modules?
Do you have any 1GB RAM modules?

If you do remove them. That will almost certainly stabilise your system. Browse this thread, we’ve repeated this many times...

 

[alpha1r]

Do you have any 512MB RAM modules?
Do you have any 1GB RAM modules?

If you do remove them. That will almost certainly stabilise your system. Browse this thread, we’ve repeated this many times...

Nope I have all matched pairs of 2GB RAM modules.