8GB DIMMS working in 2008 mac pro 3,1??? making max ram 64GB?

Personally I would trust OWC to sell all the possible acceptable ram combinations for any particular model. And since I don't see OWC selling 8GB ram for 2008 mac pro's I'm inclined to believe it won't work in 2008 mac pro's. OWC is selling only 1's, 2's, and 4's for that model.

FWIW you can always call OWC and see what their opinion is of trying to use 8GB dimms in a 2008.

I have never heard of any, and along with OWC there is Kingston and Crucial which tend to be conservative and on the safe side.

If you need more than 32GB you will want a newer Mac Pro. Lot more about RAM and performance:

http://www.macperformanceguide.com

No major manufacturer is supporting this memory configuration in the Mac Pro 3,1 (2008), and Apple certainly is not.

So if you have any problems, the eBay seller will be your ONLY source of Mac support for any unusual issues that develop.

That is not a situation I would put myself in.

I would at the least ask for a copy of the warranty so you can review the fine print. They claim lifetime warranty on the 64GB setup, but there may be details they are not disclosing.

Hi Rejon...

I know this is a bit of an old thread, but thought I'd share that I am certain this setup will. You see, I have an early 2008 Mac Pro with 4x8GB chips and 4x4GB chips. Got a really good deal on 667MHz FB chips (I know this should be taking 800MHz chips, but with an SSD RAID 0 setup and all this RAM, you could hardly tell the difference). This gives me a total of 48GB of RAM. I do not see why replacing the 4x4GB chips with 4x8GB chips would not work.

See below for the pics (I took out my Serial and UUID of course):

Anyone feel free to comment on this as it is the real deal. I am trying to secure 4 more 8GB chips to prove that 64GB in total would work in this model. Will post pics if I ever get around to it.

Regards,

FaceTimeLover

FaceTimeLover-

So the bottom line for you is that 4*8GB DIMMs CAN work in these Mac Pros, PROVIDED you are willing to drop down one click on the memory speed ??

Are these still ECC DIMMs ?

Hi Grant,

Well, I did not purchase 800MHz DIMMs, unfortunately. They were severely more expensive, but my hunch is that they would still work. The specs of the RAM read DDR2, 667MHz Fully Buffered DIMM, PC2-5300F. Do not see anything about ECC, so it's probably safe to say that it's non-ECC. This is fine for what I use my Mac Pro for anyhow. Either way, you don't find anyone advertising such capabilities regardless for a 3,1 Mac Pro anywhere (to my knowledge of course - did a brief search for it and keep coming up with "no's")...

I may be getting my hands on 4 more 8GB DIMMs tomorrow, so stay tuned for an update on whether I was able to squeeze 64GB into this 3,1...

Take care,

FTL

I actually have "seen" 8GB FBDIMMs. Thought all FBDIMMs were ECC, could be wrong.

They were designed for servers in a temperature controlled environment where they would be kept below max operating temperature.

You can buy and add RAM heatsinks and one Mac vendor sells a fan kit to put in the Riser cage.

But this is the first time I have heard of anyone putting more than 32GB in 3,1.

As for 667, the 4% hit that Barefeats found is miniscule and outweighed also by having all 8 DIMM slots populated which gets 17% boost compared to less than 8 DIMMs (number, not 8GB size).

So as long as you have say Hardware Monitor and set it to alert if any memory sensor gets a reading above 72*C - be nice to tell the fans via SmcFanControl to crank rpm up to 1200 rpm perhaps? Heat would be only issue as long as they show up and work and don't cause any trouble.

I would run some tests, and of course you can force the machine to boot 64-bit kernel in order to make best use.

Apple Pro RAID card didn't seem to like more than 48GB but then it doesn't like 3TB disk drives either. there may be other things too.

Hi all,

As promised, I was able to get my hands on four more 8GB sticks and am happy to report that my hunch was correct. All 64GB of RAM is recognized by the Mac Pro 3,1.

See below for the new pics:

Also, as hatter suggested, ECC is enabled (see below):

Unsure why this was not something that anyone ever tried previously (and reported), however, it sure is pretty cool to find out that my older Mac Pro can still hang in the RAM department!

Cheers, all,

FTL

Probably the $1500 now, and very possible a set was $2500 by the time the Nehalem architecture and DDR3 pricing.

http://eshop.macsales.com/item/Other%20World%20Computing/1333D3W8M32K/

Which is why general advice was it was probably time for a new system.

And OS X Client support 64-bit mode came in late 2009.

They're HP. No heat sink, designed for a server room that has temperature control and probably fans that are doing more work.

Just look at his thread at the top and use those -

DDR2 667MHz FB Memory RAM for Apple Mac Pro 8 Core

Hi Rejon,

Actually, the 8GB modules I am using are from Crucial and do have the typical flat aluminium heat sink on each unit that one would expect on the chips hatter describes (not the wide flared heat sinks provided by Apple). I have been running the system since my last post - 7-27-12, without one reboot and with no issues (this room is not temperature controlled). I use this rig for music production with Pro Tools 10. This applicaiton can be quite taxing, therefore, no overheating to date indicates that things are running as they should be.

I would also like to note that the distance between these chips is far greater than one would encounter in a Dell or HP server. Such servers usually place the RAM modules very close to one another. As the Mac Pro RAM usually possesses the flared larger heat sinks, there is an abundance of space left in between each chip. With that said, I am guessing that this space is actually aiding in the heat disipation.

I hope this has been helpful.

Regards,

FTL

Amazing. If the RAM 'cage' had air slots or some decent air flow to allow front-to-back - that would help too, the closed design works against cooling.

And there are 3rd party RAM heatsinks and RAM fan coolers if they were needed - but seems not to be the case.