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4GB DIMMs in 4 core 2009 MP ?

kirkbross

kirkbross

macrumors 6502a
Original poster
Mar 6, 2007
666
22
Los Angeles
I bought 2x4GB DIMMs for my workplace 2009 MP 4 core (4,1) and I discovered later that 4 core 2009 Mac Pros only support 2GB sticks and a total of 8GB.

macsale's RAM chart is misleading -- it says "8-core only" under certain upgrades, implying the other upgrades are fine for either 4 or 8 core. I should have checked Apple's website first. Arg.

Long story short is that the box is acting odd. I have 4GB sticks in slots 1 & 3 and it registers 8GB. All is fine for a few hours but then a sudden, massive latency kicks in crippling the OS and forcing me to hard power off.

1. Is this because I'm using 4GB sticks when it wants 2GB sticks?
2. How in the world can a 2009 Mac support only 8GB of RAM?? Seems so... 32 bit...

(this is my web development workplace comp and I'm reluctant to have my boss RMA the sticks for a 4x2GB upgrade).
 
I'm pretty sure you have your wires crossed here. The 4,1 supports 1GB, 2GB, 4GB, 8GB, and 16GB chips - just that I know of. And if I'm not mistaken (which I might be) that machine (4,1 with a single processor board) should support from 4 to 64GB total memory.

So if your machine is acting strange it's something else. Bad RAM, RAM needs reseating, some software conflict, other?
 
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I have the same machine (4,1 Mac Pro) as you, and before I even powered it on the first time, I opened it up, pulled the CPU tray, removed the 3x1GB sticks and replaced with 4x4GB sticks from OWC. Then about a year and a half ago, I sold off the 16GB kit and replaced it with a 32GB kit, also from OWC in the form of 4x8GB sticks. They all work fine.

You may have bad RAM or some other problem. If you troubleshot the RAM sticks one by one and found a bad one, you can send it to OWC for an immediate replacement. I had one of the 4GB sticks from the 16GB kit that was bad from OWC when I first bought my Mac Pro, and they sent me a whole new set of 4x4GB sticks, letting me return the whole bad set after verifying my new set was good, so I know that OWC's customer service is excellent.
 
So does this mean 8GB "per slot" on Apple's website?

http://support.apple.com/kb/HT4433#3

EDIT: I've traced the latency problem to Apple Mail. In Activity Monitor it was building up RAM usage every time it fetched mail from my work's mail server. I had it set to check every minute and it was adding roughly 20MB every fetch, so after several hours, Mail was using up to 7.8GB of Real Memory, crippling the system.

I deleted the com.apple.mail.plist file from user:Library:preferences and restarted Mail... now it seems to stop accumulating RAM at around 240MB.

We'll see if that does it...
 
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I don't go by Apple's outdated info, so I can't speak to the inaccuracies of something written before 16GB DIMMs came out. It's been proven by actual people physically using 16GB DIMMs that they work in single CPU Mac Pros. OSX only recognizes 48GB per CPU, whereas Windows will recognize and use 64GB on single CPU Mac Pros, including the 4,1 model. It's simply a fact.

Now, I *have* heard mention that a single CPU Mac Pro might use 64GB if 16GB of it is used in a RAMdisk. I don't believe that to be true until I see evidence of it for myself.

As far as Mail.app, well, that app was beyond annoying for me, so I deleted it. I'm a Gmail user, because it works seamlessly across my iPhone, Macs, Android and PC, even when using devices overseas. As soon as I read an email on my Android, it shows up as read on my iPhone and Macs a moment later, and vice versa. When I had Mail, it would ignore the fact that I'd read those emails already, and download/show me hundreds of unread emails in a never-ending stream of stupidity... not to mention the space it took up! I had to kill it.

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3/6 sticks is 'triple-channel' and all that, but I find that filling the slots with more RAM is far more useful than the miniscule speed benefit of three channels over two of them.
 
I have 4 x 4 GB in my Mac Pro 2009. They work without a problem. I was lucky: the invoice mentioned 1066 Mhz RAM speed but after my Hex 3.33 upgrade they show up as 1333 Mhz. :D
 
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