667 MHz v 800 MHz RAM in a Mac Pro 3,1 (Early 2008), will it make much difference?

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Level 1

8 points

667 MHz v 800 MHz RAM in a Mac Pro 3,1 (Early 2008), will it make much difference?

I know that the Mac Pro 3,1 (Early 2008) are supposed to run the 800MHz ram, but I’m aware that they also happily run the slightly less expensive 667MHz ram as well?

In the real world would you actually notice much difference between the two? Just that I have 24GB of 667MHz that I could swap over from a 2,1 model into this, or would I be better off in the long run biting the bullet and buying some 800MHz ram?

Interesting to see that OWC seem to ave some kind of exclusive deal on some 8GB 800MHz ram modules that could take the 2008 Macs up to 64GB in total! 😮😎

Mac Pro, OS X Server

Posted on Nov 28, 2013 8:24 AM

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Answer 1

Linc Davis

Level 10

209,541 points

Nov 28, 2013 11:30 AM in response to dubtastic

Never use any RAM that doesn't exactly meet the specifications for your model.

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Answer 2

The hatter

Level 9

60,980 points

Nov 28, 2013 12:28 PM in response to Linc Davis

In this case and Early 2008, 667MHz FBDIMMs have never shown to be an issue, work fine (4% hit at most, which can also be offset by using all 8 DIMM slots with four sets which improves memory bandwidth to it s best).

There have been a few 'enterprising' individuals that have had access to and used 8GB DIMMs for 32 and 64GB total memory w/o trouble but in that case you would want 800MHz DIMMs.

http://eshop.macsales.com/shop/memory/Mac-Pro-Memory#800-memory

FBDIMMs like many memory modules are not locked to a specific timing and frequency and can be backward compatible.

These from Amazon are only 2GB DIMMs but known to work in 2006-2008. When you get into 4GB the price has jumped up. And 8GB prices have been in the stratosphere, or had free access to server memory source.

2x2GB FBDIMM DDR2 667MHz @ $25

http://www.amazon.com/BUFFERED-PC2-5300-FB-DIMM-APPLE-Memory/dp/B002ORUUAC/

Komputerbay 8GB (2x 4GB) DDR2 667MHz ECC FB-DIMM (240 PIN)

http://www.amazon.com/Komputerbay-PC2-5300F-Buffered-FB-DIMM-Heatspreaders/dp/B0 05HIWD5U/

OWC 8GB FB-DIMM Memory Upgrade Kits for Apple Mac Pro 2008 Released 64GB $320

http://benchmarkreviews.com/7366/owc-8gb-fb-dimm-memory-upgrade-kits-apple-mac-p ro-2008-released/

Ideal RAM config is 8 DIMMs - offers 15% improvement memory bandwidth performance

667MHz FBDIMMs are cheap, excellent and 4% 'hit' you would never know about.

http://www.barefeats.com/harper5.html

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Answer 3

dubtastic Author

Level 1

8 points

Nov 28, 2013 12:43 PM in response to The hatter

Thanks, I thought I had read that the 667mhz ones were ok to use in the 2008 model Mac Pro.

I do like the OWC 8GB modules, but it seems that no one other than OWC stocks them (at least in the UK!) which seems strange, are they an OWC exclusive or something? They are also just a bit too pricy, but I doubt they will be coming down in price anytime soon!

Can matched pairs of 667 and 800's be used together in a 3,1 model, say 6x4gb 667 MHz and 2x2gb 800 MHz, or would I be better off opting for an additional 2x4gb 667 MHz ones to create a full house?

A full house of 8x 4gb 800 MHz ones is looking like £500

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Answer 4

The hatter

Level 9

60,980 points

Nov 28, 2013 12:57 PM in response to dubtastic

The memory controller will just as usual downclock and use the slowest MHz it detects, and it does add to the complexity.

I don't know enough about 'ranking' but that too plays a role especially in mixing different spec'd memory and brands (even different batches of same spec'd DIMM can vary too).

For UK, other than Crucial and Kingston, both usually cost more, otherwise these are ones I have heard others mention:

eBay (Europe)

http://viewitem.eim.ebay.dk/KOMPUTERBAY-8GB-2X4GB-MEMORY-for-APPLE-MAC-PRO-EARLY -2008-31-DDR2-800MHz/140962093586/item?transId=808969265004

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