Memory performance issues.

[whabang]

Hey guys. I'm stuck with on PIII system for the time being, and I only have a single stick of PC133 memory. I have plenty of PC100 lying around, and the motherboard can use them even though the FSB is 133 MHz, but is it worth lowering the RAM speed in excange for more RAM (256 vs. 640 Mb)?
I switched directly from PC100 to DDR, so I missed the big PC133-thing, and I can't say I know if that tiny increase has any major impact.

[Piru]

Depends on how much RAM you need.

If you run out of 256MB and the system begins to swap (say Windows XP), then it's well worth going for 640MB of PC100. Any RAM is faster than HDD used for swapping.

[Anonymous MOS]

Yeah, on a Windows system, more memory is better than less memory of a faster speed.


Steve

[Zac67]

Depending on the chipset, you may have to decrease FSB speed as well - downclocking the CPU by 25%. Some chipsets just won't let you run RAM slower than FSB, some give you a huge speed penalty.

Just give it a try, run e.g. CTCM with PC133, then try again with PC100.

You might even get away with overclocking the PC100 sticks to PC133 - but test well before actually using it.
Another option would be to get some PC133 used - 256 MB sticks should be very reasonably priced.

[Piru]

For memory testing I'd recommend memtest86+ which supports more chipsets and is able to report memory frequency, memory timings, and other useful information aswell. Useful when you play with memory speed and/or overclocking.

[Zac67]

Hmm, I always take the reported RAM/cache speeds from memtest86/+ with a grain of salt - on some platform I've seen them as much as 50% off... However, since you're just testing a single platform, there's nothing to worry about.  ;-)