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Powermac G5 DDR2 Dual core ram

M

mashinhead

macrumors 68040
Original poster
Oct 7, 2003
3,027
1,070
mashinhead said:
I was checking crucial for ram for the powermac. They say that the ram is PC4200 DDR2 ram, at least at all the places i've checked. But crucial offers 4200 and 5300 ram, is there a vast difference between the two, performance wise, and since i currently have a 512 stick of 4200, and if i get the 5300 stick will they work together?

http://www.crucial.com/store/listparts.asp?Mfr%2BProductline=Apple%2BPower+Mac&mfr=Apple&tabid=AM&model=Power+Mac+G5+%28Dual+2.0GHz+DDR2%29&submit=Go
Click to expand...
There's a thread just like this one with a similar question. The RAM in the new PowerMac's are of the 4200 variety, not the 5300. As such, while the 5300 may work, you won't be able to take advantage of its faster timing. I just bought the 512MB 4200 from Crucial for my recently shipped 2.0DC PowerMac. That's what's currently in it, so that's what I bought.
 
Mhaddy said:
There's a thread just like this one with a similar question. The RAM in the new PowerMac's are of the 4200 variety, not the 5300. As such, while the 5300 may work, you won't be able to take advantage of its faster timing. I just bought the 512MB 4200 from Crucial for my recently shipped 2.0DC PowerMac. That's what's currently in it, so that's what I bought.
Click to expand...
Actually it's the faster bus speed that doesn't matter. the PC 4200 at CL=4 has a faster clock speed.
The PC 5300 is CL=5. The higher the CL number, the slower that ram (at the same bus speed).
 
Ram for new dual core 2.0 GHz

I just recieved my new dual core on Monday and I installed two Corsair VS1GBKIT533D2 1GB Kit DDR2-533 PC2-4200 Value Select kits. The system has been working flawlessly for many hours this week. Depending on how much RAM you want in the future, you might consider using 1GB sticks instead of 512MB.
 
Bear said:
Actually it's the faster bus speed that doesn't matter. the PC 4200 at CL=4 has a faster clock speed.
The PC 5300 is CL=5. The higher the CL number, the slower that ram (at the same bus speed).
Click to expand...

The clock speed that the RAM is rated to handle is PC4200=533 MHz and PC5300 = 667 MHz --- but the Mac will run it at 533 MHz regardless. The term CL stands for CAS (Column Address Strobe) Latency; in brief it is the number of clock ticks that a given bank of memory has to wait to "recharge" before it is ready to do another memory operation.

CAS Latency does have an effect on performance, you are quite correct on that, all else being equal, a higher CAS latency means fewer memory operations per second, because the machine spends more time twiddling its thumbs waiting for the memory. While a higher latency will slow the machine down, there is no evidence at this stage that Apple has engineered Mac motherboards to take advantage of lower latency modules. Apple says essentially nothing about the subject other than they 'support' RAM with a range of latency settings. Now a RAM module that does CL 5 at 667 MHz shoudl probably handle CL4 at the 533 MHz speed that the Mac will run it.

So spending more for low latency RAM is 'probably' not worth it on a Mac. Spending money on higher speed (667 MHz vs. 533 MHz) RAM is definitely not worth it.

Thanks
Trevor
CanadaRAM.com
 
lesbarn said:
I just recieved my new dual core on Monday and I installed two Corsair VS1GBKIT533D2 1GB Kit DDR2-533 PC2-4200 Value Select kits. The system has been working flawlessly for many hours this week. Depending on how much RAM you want in the future, you might consider using 1GB sticks instead of 512MB.
Click to expand...
You got yours already? Damn, shipping to Canada always takes longer ;).

Why'd you decide on Corsair over Crucial?
 
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