RAM Question

[inbow78]

So my question is this. I have 2 pairs of 512MB ram. One pair is matched PC3200 400Mhz OCZ, the other pair is unmatched PC2100( I think...) . Obviously this gives me 2GB of ram, which my bios is telling me is running at Dual Channel. Am I better off just running the pair of matched PC3200 at 1GB or both pairs though unmatched at 2GB. What combination is going to give me better performance???

 

[Blain]

1GB @ PC3200 :thumbsup:

 

[pinknova]

I agree with the PC3200 at 1GB because, though you would have less RAM, the PC3200 is being slowed down to the the speed of the PC2100 otherwise. When you mix fast ram with slow ram, the faster ram has to run slower.

 

[Lord Evermore]

It might depend on what CPU you're using. If the processor isn't actually running with bus speed that can take advantage of dual channel 400MHz memory, then the 2GB option would possibly be better. Also whether you use onboard graphics, or a video card with only a small amount of onboard memory so that it uses AGP texturing or PCIe memory access makes a difference.

For example, an Athlon XP with a 266MHz bus only needs the bandwidth of a single channel of PC2100, but there are chipsets for it that can run the memory at 400MHz dual channel, and most of that goes unused.

 

[Jiggz]

Obviously your system is not running at 400Mhz FSB (or using memory ratio other than 1:1) that's why you're able to use 2Gb with 1 GB rated at PC2100 and the other rated at PC3200. If your system is such, then you're better off with 2Gb. But if you are using a memory ratio in bios to make use of the PC2100, then you'll be better off with just the 1GB PC3200 with a memory ratio of 1:1.

 

[jkresh]

depends on what you use it for, pc2100 is quite slow and if you are lowering your bus or memory ratio to use it you are slowing down your system, but if you use anything that takes more then 1gig (or if you are running vista) then pc2100 is a lot faster then virtual memory.

 

[jamesbond007]

You may want to see just how fast the PC2100 modules are being ran at when you have all 2GB installed. I have seen and installed 'PC2100' modules before that have ran at DDR200 (or 400MHz) speeds just fine with the rest of the system RAM. In other machines, it has caused the timings to increase and essentially slow the system down a bit.

If the modules are unable to keep up the pace, you could try increasing the CAS latency in the BIOS from 2 or 2.5 to say, 3.0 or 3.5 to see if the RAM will work at those latencies, but at DDR400 speeds. I recently had to adjust a friend's timings because with 4x1GB modules, the system/RAM could not keep up the DDR400 pace and defaulted to DDR333 at CAS 2.5. I adjusted the timings manually and put the CAS at 3 and set the DDR speed to 400MHz and did a little testing with MemTest86 for one run and all was well. No complaints yet!