Why is that when you fill all 4 DIMM slots...

[Philippine Mango]

And since they do this, is there any way to force the memory to run at designed speeds? I plan to run this on the intel 875P chipset.

 

[ts3433]

I believe the DDR400 specification currently allows for only one DIMM per channel, so it's supposed to do this. You can manually run the RAM out of spec, though.

 

[AristoV300]

I was able to set it manually to 400mhz on my 875P board using 4dimms. Probably becuase the memory controller is saturated. I know you won't be able to use performance mode or PAT with 4 dimms regardless of the setting in the BIOS.

 

[Accord99]

Originally posted by: Philippine Mango
And since they do this, is there any way to force the memory to run at designed speeds? I plan to run this on the intel 875P chipset.

It shouldn't on the 875P chipset, as long as all 4 DIMMs have matching SPD timings.

 

[Philippine Mango]

then what chipsets do this defaulting to DDR333 speeds? I know AMD platforms do this so...

 

[fell8]

It has to do with stability. You might be able to force it to 400 by manually adjusting the BIOS. Likely worst case is it'll work, but be unstable and freeze up. Easily fixed by clearing the CMOS (unlikely worst case is damage th the mobo and/or memory, but that's awfully unlikely).

 

[Accord99]

Originally posted by: Philippine Mango
then what chipsets do this defaulting to DDR333 speeds? I know AMD platforms do this so...

Perhaps some of the earlier S939 cpu/motherboard combos which were picky with timings. The 865/875 all support 4 DIMMs at PC3200 speeds at virtually the same performance as 2 DIMMs.

http://www.lostcircuits.com/memory/2gb/8.shtml