DDR400 to DDR200 problem

[shlemielo]

I'm running an old MSI K8N Neo Socket 754 mobo with 2x512mb sticks of Corsair PC3200 DDR 400 RAM. I bought a G.Skill 1gig stick and stuck it in the last DDR slot. Though the comp recognizes 2 gigs of RAM, it runs at DDR 200 speeds only, meaning a memory bandwidth of around a paltry 880 MB/s. I've tried rearranging the sticks, but any combination of the Corsaid plus G.Skill RAM takes me down to DDR200 speeds.

What's going on?

 

[LOUISSSSS]

what do u mean ddr 200 speeds?
as in 100mhz?

 

[shlemielo]

I'm not really sure. The memory posts as DDR 200 when used together, but if I use either the Corsair or G.Skill independently, they post as DDR 400. BIOS says 200mhz for combined memory, 400mhz when using them separately.

This is using just the Corsair: http://img403.imageshack.us/img403/3682/separateqk4.jpg

EDIT: Nevermind, I think I got it. Apparently the G.Skill RAM can't run at 2.0 CAS latency. I had to settle for 3.0

 

[Yellowbeard]

When you fully load all 3 slots on a board using that chipset, the bios drops the RAM speed due to the load. You may be able to manually clock it back up some but, it will depend heavily on your memory controller.

If you need more speed vs the full 2gb, you may do well with the Gskill in slot 1 and one of the Corsair modules in slot 3 for 1.5gb. You are just going to have to do some tuning/tweaking/testeing and see what works best for your needs.

 

[shlemielo]

I managed to get it down to 2.5CL. I do have a general question about CL timing though -- how much will this affect my FPS in older games, like Warcraft III/WoW? I noticed a significant difference between DDR200 and DDR400 (30 FPS vs 60 FPS)

 

[Yellowbeard]

CAS latency will have virtually no measurable effect on FSP. CPU cycles feeding the GPU are the key.