Questions about my memory configuration

[skruples]

Hi, I'm a new user on these forums and not very schooled in issues of hardware, so I apologize if my questions seem ignorant.

I recently bought a new computer, with 2 gigs of corsair dual ddr memory in 2 dimms. The configuration runs fine in slots 1 & 3, (bios recognizes the memory as ddr 400, dual channel, 128 bit) but if I put them in slots 1 & 2 the bios recognizes them as ddr 333, single channel, 64 bit.
I believe this is the model i have: http://www.corsair.com/corsair/products/specs/cmx1024-3200pro.pdf

Normally this wouldnt bother me, because I could simply keep them in positions 1 and 3 and all is well. However, at some point in the future I'd like the option of upgrading to 4 gigs. Is there any way to get my current ram to work at full speed with its neighbor slot occupied?

My second question has to do with my old ram, which was 2 gigabytes of corsair ddr 400, dual channel memory matched pair. To my untrained eye, my old ram and new ram seem to be identical, but my new computer does not recognize the old ram at all. I tried installing just my old ram, and the computer will not even post. Is this some hardware incompatibility? Or have I made an error somewhere in the bios?
This is the model of my old memory, im sure the corsair website's description is better than mine.
http://www.corsair.com/corsair/products/specs/TWINX2048-3200C2PRO.pdf

Any help is appreciated, and I'm sorry if this post is redundant but in my hours of searching the internet I couldnt find anything that helped my specific problem.

My hardware configuration:
Asus A8N-SLI premium
AMD x2 4800
2 gb corsair dual channel ddr400
geforce 6200 (with turbocache)
creative x-fi xtrememusic
2x Western Digital 740GD Raptor 74GB in raid 0
thermaltake 680 watt power supply

 

[mpjesse]

Answer to question 1: I have the same board you do. It's a BIOS glitch. You can simply go into the BIOS and force the correct timings. It works without a hitch. (I have to do it myself.) There's a BIOS update for this problem, but IMO it's just easier to force the settings and save them. As for single channel, you have to put the DIMMs in Slots 1 and 3 to get dual channel. Almost every motherboard works like this. Dual channel does not work w/ DIMMs in slots 1 & 2. Your mobo manual will tell you this. And yes, don't worry, when u upgrade to 4GB all the memory will work in dual channel. I promise.

Answer to question 2: Those memory modules are completely different. The only thing they have in common are they're both DDR400. I think you're problem may be the major difference in timings. Your new RAM is rated at CAS 3 (3-4-4-8 timings) while your old RAM is rated at CAS 2 (2-3-3-6 timings). I would try forcing the timings in ur BIOS to 3-4-4-8 timings and set them to 2T. Then install the old RAM and see if it works. Motherboards are supposed to figure this out on their own- but 50% of the time they don't... esp if there was different RAM in the system. You might also try swapping the DIMMs around. Make sure you have this setup: New RAM in Slots 1 and 3, old RAM in slots 2 and 4. Or vice versa. However, do not do this: 1 new DIMM in Slot 1 and 1 old DIMM in slot 2, 1 new DIMM in lot 3 and one old DIMM in slot 4.

Make sense?

-mpjesse

Note, you'd be better off running the old RAM in Slots 1 and 3. The timings are much, much better. Clear the BIOS when you switch from the old to the new. Look up how to do it in ur motehrboard manual.

 

[skruples]

Ok, as per your advice I stuck the 2 old Dimms in slots 2 and 4, and set the memory timings to manual instead of auto, and that seems to have made the system recognize that they exist. They're all running at what seems to be full speed (ddr400 dual channel 128 bit). Windows thinks theres only 3 gigs available, but from what ive read thats a 32bit windows issue.

As for my old memory having better timings, dont i have to force them to run at the worse timings so my new ram can keep up? Also, you said "However, do not do this: 1 new DIMM in Slot 1 and 1 old DIMM in slot 2, 1 new DIMM in lot 3 and one old DIMM in slot 4." which i think is exactly what ive done, is this a bad thing? My current setup has the NEW CAS3 ram in slots 1&3, and my old stuff in 2&4. Bios is set for CAS3.

Thanks a bunch for your help so far, i definitely wouldnt have figured this out on my own

 

[Crashman]

Channel One is slots 1 and 2, Channel Two is slots 3 and 4, so 1-3 is dual-channel first pair, 2-4 is dual-channel second pair.

As for your current configuration, you actually want the slowest RAM in slots 1-3 and the faster RAM in slots 2-4.