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667 MHz DDR2 vs. 800 MHz DDR2 in New Mac Pros

F

Firefly2002

macrumors 65816
Original poster
According to Barefeats.com, using 667 MHz FB-DIMM RAM in the new Mac Pros come with a minimal performance hit that you would never notice in real life- and in some cases, no hit at all.

http://barefeats.com/harper5.html

Since 667 MHz DIMMs are still somewhat cheaper than 800 MHz DIMMs, I thought it might be something to consider. This would be for new buyers, of course, as it wouldn't make a great deal of sense to try mixing 800 MHz DIMMs with 667s.
 
It would be beyond stupid in my opinion to cripple your top of the line workstation all in the name of saving $200. If you can afford a $3,000 Mac Pro you can afford the correct spec ram. 🙄

Also, who trusts a few benchmarks? There are too many variables in a proper test that defines all sorts of situations not just a few proven in the benchmarks. People who purchase Mac Pro's do not just browse the web and read email... There are many other tasks/applications that may take advantage of the 800mhz ram.

Buy 800mhz ram, unless you've blown your life savings on a Mac Pro and can only afford inferior 667mhz ram.
 
Cripple? In the real-world tests the performance difference was generally 0.0%. The highest difference it made was what, 12%? That's not something you can notice.

I said it was something to think about, not that you should all go do it. The idea was that you pay less for virtually no performance hit.

800 MHz isn't the "correct spec," per se, it's just the maximum speed. Obviously, the board supports 667 MHz DIMMs, or they wouldn't run. And since it looks like the extra memory bandwidth isn't really an issue, it's not crippling the system.

A Mac Pro with 16GB worth of RAM in 8 slots populated would get better performance than 16GB in 4 slots. My point is things that make a difference are more along the lines of how you populate your Mac with memory, not whether or not you run 667 or 800 MHz FB-DIMMs in your Mac (apparently).

And again, this was based on a limited suite of benchmarks and real-world tests. I never said it was a sure thing.

And not everyone sees things the way you do; some people like saving money they really don't have to spend regardless of whether they can afford it or not. Actually, most do.
 
Firefly2002 said:
Cripple? In the real-world tests the performance difference was generally 0.0%. The highest difference it made was what, 12%? That's not something you can notice.

I said it was something to think about, not that you should all go do it. The idea was that you pay less for virtually no performance hit.

800 MHz isn't the "correct spec," per se, it's just the maximum speed. Obviously, the board supports 667 MHz DIMMs, or they wouldn't run. And since it looks like the extra memory bandwidth isn't really an issue, it's not crippling the system.

A Mac Pro with 16GB worth of RAM in 8 slots populated would get better performance than 16GB in 4 slots. My point is things that make a difference are more along the lines of how you populate your Mac with memory, not whether or not you run 667 or 800 MHz FB-DIMMs in your Mac (apparently).

And again, this was based on a limited suite of benchmarks and real-world tests. I never said it was a sure thing.

And not everyone sees things the way you do; some people like saving money they really don't have to spend regardless of whether they can afford it or not. Actually, most do.
Click to expand...

I honestly couldn't be bothered to save a buck. I get the best currently available and write it off as a business expense. I upgrade when I need to. I will stick with my 800mhz ram, good luck to those looking to save maybe $150 with 667mhz ram. By all means, if you think it is not beneficial and if that small amount really means that much to you, go for it.

All I was saying is that for such a small price difference, you might as well stick to 800mhz ram. The same was said for the 8 core vs 4 core. For the $500 difference you get hardware essentially worth $800 I think someone said. That's what the processor costs alone. Same goes for the 8800GT, twice the performance, for $160 more (with student discount).
 
Not a chance...

Personally I think you would be risking your new computer for very little savings. RAM problems are notoriously hard to diagnose, especially in the middle of a tight timeline and that document that was due 10 minutes ago disappears into a cascade of corrupted bits. In a workstation class computer like the Mac Pro, hobbling it with inferior RAM makes very little business sense.

Another thing to consider is how much additional heat will be generated with these chips running them above spec. Memory chips are sorted at the production facility by batches as they come off the assembly line, if the chips fail to maintain spec at one speed they are downgraded to a lower speed. Pushing chips to perform beyond their specs may work in the short term, but if they overheat they can cause irreparable damage to the riser board that the memory fits into. If you think the price difference between the 667 and 800MHz chips is excessive, try tacking on a riser board replacement as well, and good luck getting that replaced under a warranty.
 
I imagine the price difference between the two types was larger when this thread was last alive since that was a year ago just after the Early 2008 MPs were released, hence the OP's desire to minimize costs. Your comments are no doubt valid- and probably why there was not more discussion about this at that time since few people would doubt that trying to save a dollar that way does not make sense.
 
12%? that's ****ing loads. if it takes 6 hours to export a long HD video, then that's 45mins of wasted time
 
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