iM 4,1-14,4 2011 iMac Graphics Card Upgrade

[bielousov.com]

No, my ODD is there.
My two SSDs is glued together in original HDD bay

After several tests I realized that Apple did a very great job about air flow inside iMac...
Without ODD, air pressure is low and temperature at GPU heatsink is always 3 degrees higher.

So I put back my ODD (doesn't work at all) only to get correct airflow.

Oh, good to know. Well since you have a potentially free ODD and 5V SATA cable, you could replace it with a blower to build up a pressure on the heat sink I guess.

Could you please elaborate on your 3800rpm fan mod? Did you just cut the sensor cable and now your sensors read 3800 on the same (2500rpm) fan? How do you know it's true 3800 rpm, but not just what it shows for 0 signal (like 129° GPU die value)?

 

[Ri7]

Well since you have a potentially free ODD and 5V SATA cable, you could replace it with a blower to build up a pressure on the heat sink I guess.

Could you please elaborate on your 3800rpm fan mod? Did you just cut the sensor cable and now your sensors read 3800 on the same (2500rpm) fan? How do you know it's true 3800 rpm, but not just what it shows for 0 signal (like 129° GPU die value)?

Speaking of the devil, I have a feeling that if we had a die temp, the overheat would not be an issue. Again, the theory: assume some kind of FakeSMC is used that links up GPU die temp to the Heatsink sensor reading and let's say that heatsink 74°C = die 93°C (that's where default thermal throttling is set in BIOS). So Whenever heatsink goes above that, Mac SMC reads high die temp that is reported to GPU and the throttling is applied.

Let's put things in place...
I have a topic about this issue:

Weird maximum fan RPM values after each reboot

Hi all! My signature setup (with K4100m) is acting weird about fan speeds. Each time I turn on my system it shows different maximum rpm speeds for ODD and CPU fans. With K4100m GPU I really need maximum rpm from ODD fan, but sometimes it shows 3800rpm (that is OK) but sometimes it shows only...

forums.macrumors.com

I did tests with other fans, but no fan is better than stock one. Believe me! lol
Even pipes, duct tape, gamer fans, nothing could beat apple fan in my tests.

It's very easy to know it's running more than 2500rpm: is is VERY loud! As loud as HDD fan at maximum speed.
If you get a 2009/2010 iMac you will find the same behaviour

Again: RPM sensor and TEMPERATURE sensor are different thing and each one have it's own wires.
I've disconnected TEMPERATURE sensor cable and the consequence is well known: fan blowing at maximum speed all the time. Imediately noted by the sound that it's more (3800rpm) than original firmware can do (2500rpm).

Macs Fan app shows real speed reported by ODD Fan RPM sensor and I'm using GPU heatsink value to control it.

Speaking about GPU DIE temperature, it can be readed in Windows. Delta temperature between DIE and Heatsink here is about 4 to 5 degrees only. I've done some measurements with laser thermometer to ensure readings was something real too.

No throttling here at all.

 

[bielousov.com]

Let's put things in place...
I have a topic about this issue:

Weird maximum fan RPM values after each reboot

Hi all! My signature setup (with K4100m) is acting weird about fan speeds. Each time I turn on my system it shows different maximum rpm speeds for ODD and CPU fans. With K4100m GPU I really need maximum rpm from ODD fan, but sometimes it shows 3800rpm (that is OK) but sometimes it shows only...

forums.macrumors.com

I did tests with other fans, but no fan is better than stock one. Believe me! lol
Even pipes, duct tape, gamer fans, nothing could beat apple fan in my tests.

It's very easy to know it's running more than 2500rpm: is is VERY loud! As loud as HDD fan at maximum speed.
If you get a 2009/2010 iMac you will find the same behaviour

Again: RPM sensor and TEMPERATURE sensor are different thing and each one have it's own wires.
I've disconnected TEMPERATURE sensor cable and the consequence is well known: fan blowing at maximum speed all the time. Imediately noted by the sound that it's more (3800rpm) than original firmware can do (2500rpm).

Macs Fan app shows real speed reported by ODD Fan RPM sensor and I'm using GPU heatsink value to control it.

Speaking about GPU DIE temperature, it can be readed in Windows. Delta temperature between DIE and Heatsink here is about 4 to 5 degrees only. I've done some measurements with laser thermometer to ensure readings was something real too.

No throttling here at all.

Unfortunately I had all kinds of issues installing Windows with either RAID 0, Fusion Drive or APFS, still didn't make it work, so I was messing with the BIOS in Parallels, but that sure didn't provide the GPU access as it is virtualized.

Anyways that makes perfect sense. I thought you were cutting the rpm sensor 🤦‍♂️ .
Weird that FanControl doesn't let it go up to 3800 then. But oh well.
Ok, where's my screwdriver kit? See you in an hour…

 

[Ausdauersportler]

Unfortunately I had all kinds of issues installing Windows with either RAID 0, Fusion Drive or APFS, still didn't make it work, so I was messing with the BIOS in Parallels, but that sure didn't provide the GPU access as it is virtualized.

Anyways that makes perfect sense. I thought you were cutting the rpm sensor 🤦‍♂️ .
Weird that FanControl doesn't let it go up to 3800 then. But oh well.
Ok, where's my screwdriver kit? See you in an hour…

Disconnect one of your drives and try to install Windows (UEFI mode) again! For unknown reasons the format utillty used in the Windows installer dialogue quits working if more than one drive has been installed. I am pretty sure I posted this before.

 

[Ausdauersportler]

WINDOWS 10 UEFI INSTALLATION

This methods works on Mid 2010 and even on Mid 2011 unless you have installed a second disk into your 2011 iMac!! So the solution will be to disconnect the second HDD/SDD during the installation process.

https://gist.github.com/oznu/8796d08d73315483c3b26e79a8e3d350

The only thing to do is is this:

Within the initial Win10 installation dialog the prepared FAT partition is shown. Just delete this partition creating some free space on the disk, select this free space and press proceed. The installer creates new a single NTFS and some helper partitions and starts with copying the data from the USB to the NTFS partition.

Having a second SSD/HDD connected to the system creates this error.

 

[ChrisCaro]

@ChrisCaro (iMac mid 2011, 27", iMac12,2)
Good job getting legacy win10 to co-operate; @Ri7 has had good success with the oc vbios. I have it currently on a 2011, very stable running cool @967mhz for GPU, 2200mhz for mem with 0.975v.
Make sure you have:
Bootrom: 87.0.0.0.0
SMC ver: 1.72f2

Never realized that Legacy Win10 didn't like to cooperate!

Bootrom and SMC check out. Some additional Detail, MacOS would boot normally with the UGA rom- no issues at all! it was only Windows that suffered a problem. Don't spend any of your time trying to figure it out- bigger fish to fry! The performance boost is not a requirement on my end.

maybe related, nvflash_linux over ssh had some unique quirks when i flashed back to the BR.rom. even though i navigated to the directory where nvflash_linux was, linux would try to look for the command in the root folder. easy fix, just had to use the entire directory location when executing the command and pointing where the rom was.

 

[Ausdauersportler]

Never realized that Legacy Win10 didn't like to cooperate!

Bootrom and SMC check out. Some additional Detail, MacOS would boot normally with the UGA rom- no issues at all! it was only Windows that suffered a problem. Don't spend any of your time trying to figure it out- bigger fish to fry! The performance boost is not a requirement on my end.

maybe related, nvflash_linux over ssh had some unique quirks when i flashed back to the BR.rom. even though i navigated to the directory where nvflash_linux was, linux would try to look for the command in the root folder. easy fix, just had to use the entire directory location when executing the command and pointing where the rom was.

This is one of the simple security measures included in every UNIX style operating system when you act as a classical root user - which had and has total control over the system. Since this user can even delete the complete root file system with a simple rm -rf / it is a good idea to call as a root user programs only with an absolute path or located in system known locations. Then you know which version of the program you are going to use.

So this is not a quirk. It works as designed.

 

[bielousov.com]

Unfortunately I had all kinds of issues installing Windows with either RAID 0, Fusion Drive or APFS, still didn't make it work, so I was messing with the BIOS in Parallels, but that sure didn't provide the GPU access as it is virtualized.

Anyways that makes perfect sense. I thought you were cutting the rpm sensor 🤦‍♂️ .
Weird that FanControl doesn't let it go up to 3800 then. But oh well.
Ok, where's my screwdriver kit? See you in an hour…

Holy ****… what a difference it made!
So thinking about the air pressure @Ri7 mentioned, I duct taped all the holes I had in my HDD OWC chassiss in ODD bay (see the before and after photos attached). Duct taped the narrower airflow and any losses that I had between the fan and HDD (mind I don't have an iMac chassis, but rather reused one from MBP) and disconnected the ODD temp sensor of course.

Now FanControll indeed sees the ODD max @3800rpm (and it sounds like it) which I linked to the heatsink 60° range and now I never even get to 60 under heavy load (previously it was 75°). I'm gonna try the original @nikey22 (BR2) ROM again, this cooling mod looks promising enough.


UPDATED
So I did roll back to 780M_BR2 and it works like a charm now, after 1 hour on the high settings on native 2k resolution the heat sink was at 62°. @nikey22 I guess you could post both ROMs on the top thread, with a note that BR2 has ~10% overclocking and requires cooling improvement (you kinda said it about k5 anyways, but it might need more than that).

Now 780M is totally usable and I sure didn't expect to get it overclocked when I started this upgrade, but it is!
How cool is that?

 

[Reno12]

Use systems preferences -> start object to choose the Catalina Loader on your SD card as the standard boot object. Everything else has been written down several times before either on the first post or in the linked posts from there.

This is no EFI Boot screen and alt/option on boot will not work!!

I’m confused with current situation after GPU swap. Here is a short summary of facts and my conclusions and still open questions. As i am a beginner in OC and iMac boot stuff I would appreciate if more experienced user can orient my investigations

What the Imac Does / Did :

• Before running WX4150 card, the iMac ran a k2100m w/o OC. HS and Catalina installed on SSD.
• It posts in every case : with or w/o SSD plugged on sata
• With OC on SD card and SSD plugged on external USB port it boots and I can run MacOS (at least Catalina, I did not try HS). I have brightness control. I’m writing currently with that setup.
• ODD runs
• It runs Unigine Valley with adequate results (FPS=38 score=1588)
• It lights on 3 internal leds 1, 2 & 4
• If I boot on a USB BigSur Installer created with MicropatcherAutomator (w/o SSD) I get the Hedgehog icon.

What the Imac Doesn’t

• It does not show an EFI boot picker (that is the expected behaviour of AMD card)
• with SSD plugged on SATA cable the Imac does not boot MacOS with or w/o OC on SD card. Screen turns on and hangs. Even if I wait 2 min
• with SSD plugged on external USB port and w/o OC on SD card, the iMac does not boot MacOS and shows same behaviour : screen turns on and hangs.
• At step 13 of herrdude's guide (post #5336) the iMac refuses to reboot after selection of MacOS on Catalina Loader. It shows the error message « You cannot modify the boot volume. NVRAM tool cannot determine a preference… see picture ». I have prepared the Catalina loader with Disk Utility

My CPU is a Xeon L3426 (w/o iGPU) as I wanted to have lowest possible TDP : does it play a role for the boot sequence ?

I’ve read posts #12556 from davidg5678 suggesting I might have a kind of short between GPU and heatsink. A kapton tape covering might help.

My understanding is :

• the SSD is ok
• I need first an EFI boot in order to select the correct boot sequence on SD card
• the SATA PSU or the SATA cable of SSD are defective

What I could do :

• buy a miniSATA/SATA adapter and connect the SSD to the ODD cable
• change the SATA cable of SSD
• open the iMac again and put additional tape on GPU to avoid short (I have put a 1mm copper plate on Die)

Do you see flaws in my thinking? Do you have any additional hints for me ?

Thanks
Renaud

 

[Ausdauersportler]

I’m confused with current situation after GPU swap. Here is a short summary of facts and my conclusions and still open questions. As i am a beginner in OC and iMac boot stuff I would appreciate if more experienced user can orient my investigations

What the Imac Does / Did :

• Before running WX4150 card, the iMac ran a k2100m w/o OC. HS and Catalina installed on SSD.
• It posts in every case : with or w/o SSD plugged on sata
• With OC on SD card and SSD plugged on external USB port it boots and I can run MacOS (at least Catalina, I did not try HS). I have brightness control. I’m writing currently with that setup.
• ODD runs
• It runs Unigine Valley with adequate results (FPS=38 score=1588)
• It lights on 3 internal leds 1, 2 & 4
• If I boot on a USB BigSur Installer created with MicropatcherAutomator (w/o SSD) I get the Hedgehog icon.

What the Imac Doesn’t

• It does not show an EFI boot picker (that is the expected behaviour of AMD card)
• with SSD plugged on SATA cable the Imac does not boot MacOS with or w/o OC on SD card. Screen turns on and hangs. Even if I wait 2 min
• with SSD plugged on external USB port and w/o OC on SD card, the iMac does not boot MacOS and shows same behaviour : screen turns on and hangs.
• At step 13 of herrdude's guide (post #5336) the iMac refuses to reboot after selection of MacOS on Catalina Loader. It shows the error message « You cannot modify the boot volume. NVRAM tool cannot determine a preference… see picture ». I have prepared the Catalina loader with Disk Utility

My CPU is a Xeon L3426 (w/o iGPU) as I wanted to have lowest possible TDP : does it play a role for the boot sequence ?

I’ve read posts #12556 from davidg5678 suggesting I might have a kind of short between GPU and heatsink. A kapton tape covering might help.

My understanding is :

• the SSD is ok
• I need first an EFI boot in order to select the correct boot sequence on SD card
• the SATA PSU or the SATA cable of SSD are defective

What I could do :

• buy a miniSATA/SATA adapter and connect the SSD to the ODD cable
• change the SATA cable of SSD
• open the iMac again and put additional tape on GPU to avoid short (I have put a 1mm copper plate on Die)

Do you see flaws in my thinking? Do you have any additional hints for me ?

Thanks
Renaud

Yes, search back! You will find out that the 4150 has exactly this problems.

We had other similar reports and as I remember there is also a warning about the difficulties to get the (HP) WX4150 working in (21.5“) iMac models in general.

History is repeating, obviously these reports too.

 

[herrdude]

I’m confused with current situation after GPU swap. Here is a short summary of facts and my conclusions and still open questions. As i am a beginner in OC and iMac boot stuff I would appreciate if more experienced user can orient my investigations

What the Imac Does / Did :

• Before running WX4150 card, the iMac ran a k2100m w/o OC. HS and Catalina installed on SSD.
• It posts in every case : with or w/o SSD plugged on sata
• With OC on SD card and SSD plugged on external USB port it boots and I can run MacOS (at least Catalina, I did not try HS). I have brightness control. I’m writing currently with that setup.
• ODD runs
• It runs Unigine Valley with adequate results (FPS=38 score=1588)
• It lights on 3 internal leds 1, 2 & 4
• If I boot on a USB BigSur Installer created with MicropatcherAutomator (w/o SSD) I get the Hedgehog icon.

What the Imac Doesn’t

• It does not show an EFI boot picker (that is the expected behaviour of AMD card)
• with SSD plugged on SATA cable the Imac does not boot MacOS with or w/o OC on SD card. Screen turns on and hangs. Even if I wait 2 min
• with SSD plugged on external USB port and w/o OC on SD card, the iMac does not boot MacOS and shows same behaviour : screen turns on and hangs.
• At step 13 of herrdude's guide (post #5336) the iMac refuses to reboot after selection of MacOS on Catalina Loader. It shows the error message « You cannot modify the boot volume. NVRAM tool cannot determine a preference… see picture ». I have prepared the Catalina loader with Disk Utility

My CPU is a Xeon L3426 (w/o iGPU) as I wanted to have lowest possible TDP : does it play a role for the boot sequence ?

I’ve read posts #12556 from davidg5678 suggesting I might have a kind of short between GPU and heatsink. A kapton tape covering might help.

My understanding is :

• the SSD is ok
• I need first an EFI boot in order to select the correct boot sequence on SD card
• the SATA PSU or the SATA cable of SSD are defective

What I could do :

• buy a miniSATA/SATA adapter and connect the SSD to the ODD cable
• change the SATA cable of SSD
• open the iMac again and put additional tape on GPU to avoid short (I have put a 1mm copper plate on Die)

Do you see flaws in my thinking? Do you have any additional hints for me ?

Thanks
Renaud

Ummmmmmm, in Step 13 I said that you cannot choose the Start Up Disk. It is in the screenshot that you took! You have to boot holding Alt/Option and then choose the Catalina Loader (CTRL + Enter) if you want that to be your default boot option.

 

[Ausdauersportler]

Ummmmmmm, in Step 13 I said that you cannot choose the Start Up Disk. It is in the screenshot that you took! You have to boot holding Alt/Option and then choose the Catalina Loader (CTRL + Enter) if you want that to be your default boot option.

There is not alt/option boot screen with AMD card unless you choose the EG BIOS with an external screen connected.

 

[nikey22]

@bielousov.com
good to know!
I thought the _BR2 rom was okay, me, @Ausdauersportler and @highvoltage12v have used it for almost 2 yrs now without crashes and since there are plenty of 780Ms around, more people would have spoken up if it was a reproducible issue. Possibly as you've discovered, it is a fringe phenomenon apparent only at extremes of gpu stress. I will put the rom back up. I am doing some additional fine tuning mods to it first, I want to get rid of the SLI code, we don't need it! (I'm sure there were some laptop PCs that were capable of this, wow!). Also, I want to make sure Eplida vram latencies are working well incase anyone has a Eplida based card and I'll double check the Samsung entries.

Relocating the ODD sensor was an excellent tweak per @Ausdauersportler, I use this routinely now on all my tests. I like what you and @Ri7 are doing with the airflow analysis, so much depends on it. I am currently looking into the SMC firmware (very dangerous by the way) to see if there is anything that I can reset the RPMs for the fans to a different threshold. Dangerous because if you mess up the firmware in the SMC, you will have to get another donor board to get back the functionality. You can't simply buy one, they all come unprogrammed. Furthermore the SMC chip will need solder balls via a stencil. The fun never ends!

 

[OnawaAfrica]

Unfortunately I had all kinds of issues installing Windows with either RAID 0, Fusion Drive or APFS, still didn't make it work, so I was messing with the BIOS in Parallels, but that sure didn't provide the GPU access as it is virtualized.

Anyways that makes perfect sense. I thought you were cutting the rpm sensor 🤦‍♂️ .
Weird that FanControl doesn't let it go up to 3800 then. But oh well.
Ok, where's my screwdriver kit? See you in an hour…

For me to install Win10 in efi mode I added a Partition (Not Volume) on my macOS SSD and formatted it fat32 then I booted win10 installer from usb and Formates the fat32 partition with disk part. Then I installed windows with DISM instead of the installer. All works well however I had to block windows from trying to install intel iGPU drivers via Group Policy’s otherwise I would get BSOD showing iGPU DRIVER crash

 

[m0bil]

This is the one I have:

DELL Nvidia GeForce GTX 780M 4GB DDR5 MXM 3.0 Type B for Alienware | eBay

Find many great new & used options and get the best deals for DELL Nvidia GeForce GTX 780M 4GB DDR5 MXM 3.0 Type B for Alienware at the best online prices at eBay! Free shipping for many products!

www.ebay.ca

Appears to be Samsung. I did not confirm with the actual card received though.

Thanks to you and @nikey22 I'll be testing over the weekend a 780m I had stored as "not reliable" as it caused kernel panics under heavy stress (Unigine Valley ultra quality or long gaming sessions from kids . Hopefully with new timings it will be stable. Will post results on a couple of days. From my notes mine had Hynix BFR vram, will check that too.



May I ask what temperatures are you getting on your card with latest rom, when under stress (GPU die, and GPU heatsink) ?

 

[Ri7]

Holy ****… what a difference it made!
So thinking about the air pressure @Ri7 mentioned, I duct taped all the holes I had in my HDD OWC chassiss in ODD bay (see the before and after photos attached). Duct taped the narrower airflow and any losses that I had between the fan and HDD (mind I don't have an iMac chassis, but rather reused one from MBP) and disconnected the ODD temp sensor of course.

Now FanControll indeed sees the ODD max @3800rpm (and it sounds like it) which I linked to the heatsink 60° range and now I never even get to 60 under heavy load (previously it was 75°). I'm gonna try the original @nikey22 (BR2) ROM again, this cooling mod looks promising enough.


UPDATED
So I did roll back to 780M_BR2 and it works like a charm now, after 1 hour on the high settings on native 2k resolution the heat sink was at 62°. @nikey22 I guess you could post both ROMs on the top thread, with a note that BR2 has ~10% overclocking and requires cooling improvement (you kinda said it about k5 anyways, but it might need more than that).

Now 780M is totally usable and I sure didn't expect to get it overclocked when I started this upgrade, but it is!
How cool is that?

Great!
I'm really happy reading this!

Correct air flow plays a very important role in temperatures, even without fan speed mod.
Another very important thing is to keep temperature delta between heatsink and die as low as possible (for me it's 4°C to 5°C degrees).

With this delta (and K5/Grizzly) I can use 2500rpm limit without problems, as long as airflow is corrected.
I recommend trying overclocks in a methodical way, taking notes and doing stress tests and using Windows 10.
When you find it, then you repeat stress test in MacOS. In some tests here, MacOS runs a little bit hotter than Win10.

Another thing to look for is PSU temperature. Maybe you need to speed up your CPU Fan a little bit to avoid overheating PSU or start to make buzz noises. Despite CPU is running cool, PSU is always hot and use the same air flow from CPU. But this is an off-topic.

 

[NetRocker]

I read the forum and watched the video. Profit.
Thanks.

 

[OnawaAfrica]

View attachment 1736057

I read the forum and watched the video. Profit.
Thanks.

now if u like u can update even to Big Sur with Open Core

 

[NetRocker]

now if u like u can update even to Big Sur with Open Core

Do you think it will work as fast as the Sierra on my Mac?

 

[OnawaAfrica]

Do you think it will work as fast as the Sierra on my Mac?

am using Big Sur on my iMac mid-2011 21.5" with i5-2400s, 14gb Ram, 500GB Samsung EVO SSD and Nvidia Quadro K610M and its running super fast no issues at all

 

[bielousov.com]

Thanks to you and @nikey22 I'll be testing over the weekend a 780m I had stored as "not reliable" as it caused kernel panics under heavy stress (Unigine Valley ultra quality or long gaming sessions from kids . Hopefully with new timings it will be stable. Will post results on a couple of days. From my notes mine had Hynix BFR vram, will check that too.



May I ask what temperatures are you getting on your card with latest rom, when under stress (GPU die, and GPU heatsink) ?

Yeah, the problem is that the ROM that was shared here has been overclocked (~10%) and my ODD bay modification has been compromising the cooling.

Previously (i.e. overclocked) I had it going above 75° on heaatsink (don't have Windows and therefore don't have die reading) in like 10 min (Wasteland 3 @ 1920x1080 Minimal quality, Unigene Valley @ 2k Ultra) and crashing at exact same time.

After lowering frequencies I was getting ~70–72°C top on heatsink in same conditions and able to run Wasteland with no crashes at 1920x1080 any settings. After applying the cooling mod described above I'm getting 58°C heatsink on the same ROM (62°C with the overclocked one). So definitely make sure that ALL air from ODD fan goes to the heatsink and none is dispersed, also speed it up by disconnecting ODD sensor.

After the cooling mod I reverted back to the overclocked ROM and ran Wasteland 3 at 2k 8xAAF Ultra quality for a long time.

I've got 1 crash eventually, but the load has been extreme, I had to tolerate ~17fps for an hour and to be honest it didn't crash in the game, but when I switched to OS to do stuff (with the game running in BG). Same happened with the stock frequencies, no cooling mod. It seems like the delta between die and heatsink may be growing out of control eventually under extreme load.

Not tested but I'm pretty sure that the stock frequency (or even a less aggressive overclock) with the cooling mod would make it 100% reliable, but I'm fine tolerating the higher performance at a cost of a possible crash under long extreme load for now.

Unigene Valley has been stable ever since on Ultra, 2k 8xAAF in all versions except the overclocked with no cooling mod.

 

[ChrisCaro]

I was getting ~70–72°C top on heatsink (don't have Windows and therefore don't have die reading).
But with the cooling mod described above I'm getting 58°C heatsink with the lower frequencies and 62°C with the overclocked.

Occasionally if I run a demanding game (like 760M in min requirements) at 2k 8xAAF, Ultra quality, it may still crash, seems like the delta between die and heatsink may be growing out of control, both with original clocks no cooing mod and overclocked with cooling mod. But it's not fun to play at those settings anyways.

Unigene Valley has been stable ever since on Ultra, 2k 8xAAF.

For reference, I use k5pro on vram and kryonaut on die and see a 5C delta between heat sink and Die.

 

[bielousov.com]

Great!
I'm really happy reading this!

Correct air flow plays a very important role in temperatures, even without fan speed mod.
Another very important thing is to keep temperature delta between heatsink and die as low as possible (for me it's 4°C to 5°C degrees).

With this delta (and K5/Grizzly) I can use 2500rpm limit without problems, as long as airflow is corrected.
I recommend trying overclocks in a methodical way, taking notes and doing stress tests and using Windows 10.
When you find it, then you repeat stress test in MacOS. In some tests here, MacOS runs a little bit hotter than Win10.

Another thing to look for is PSU temperature. Maybe you need to speed up your CPU Fan a little bit to avoid overheating PSU or start to make buzz noises. Despite CPU is running cool, PSU is always hot and use the same air flow from CPU. But this is an off-topic.

PSU is definitely in the question. Noticed it heating up the day I plugged 780M, it's a bit better now since the LED backlight control is added, can be further reduced as the overclocked ROM has almost double the power (current) consumption than stock and even the original ROM is more that double hungry than stock AMD.

CPU fan is sure one way to tame it, I wonder if there's a better fay.

 

[ChrisCaro]

PSU is definitely in the question. Noticed it heating up the day I plugged 780M, it's a bit better now since the LED backlight control is added, can be further reduced as the overclocked ROM has almost double the power (current) consumption than stock and even the original ROM is more that double hungry than stock AMD.

CPU fan is sure one way to tame it, I wonder if there's a better fay.

You could cut open the sheathing on a standard power cord and put a clamp on style ammeter around one of the conductors to measure the current. Multiply by your voltage and you can calculate the watts. That is wattage input to the power supply, which I'm sure can be well over 300watts since I doubt it's anywhere near 100% efficiency. But maybe you could estimate the power draw..... Or just buy one of those plug-in kill-a-watt meters!

Maybe a software solution? ive seen unigine benchmarks that show the gpu wattage real time....

I've noticed that my PSU starts making worrisome electrical buzzing noises if it gets too warm. I'm guessing it's a coil or capacitor vibrating.

 

[anton74]

@anton74 (iMac mid 2010, 21.5", iMac11,2)
I'm not sure you can get QuickSync to work on your CPU. It may not have a built in iGPU.
have a read here: QuickSync, via @highvoltage12v
Make sure you have:
Bootrom: 99.0.0.0.0
SMC ver: 1.64f5

Why then do others (with the same I7860S processor and 1100M video card) have about 21 FPS in the Valley. Do I have about 5 FPS? What could be the reason? (Bootrom: 99.0.0.0.0, SMC ver: 1.64f5, BOOT SCREEN and dimming fully work)