Sigle Sided vs Double Sided Memory for 875/865...

[daos]

here is Intels own white paper on which configuration is best. ive seen some confusing debates on this forum and it got me worried. the last thing we want here is people to be confused and getting wrong information.

just for the record...Double sided memory is ALWAYS best on 865/875 chipset when using DDR400. possibly 4 DS Dimms, and then 2 DS Dimms. here is the white paper from Intels own. you will need to scroll down to Performance and read the table.

ftp://download.intel.com/design/chipsets/applnots/25273001.pdf

[Cytomax]

thanks for the link

[larva]

The point you are missing is that although double sided dimms or 4 single sided dimms performs best, it does not necessarliy overclock the best. When you are running extreme fsb to max out the cpu, as close to syncronous memory speed as possible, as low as memory timings as possible, and performance enhancement like PAT, it's really tough on the ram. If double sided dimms help your memory performance by 10% but hurt your fsb by 10%, you lose overall.

The real problem here is 12x is just not enough multiplier. Even the 16 of the 3.2GHz chip is just barely enough. We don't need to run the memory in excess of 400MHz for the memory's sake, but in the attempt to make enough fsb to deal with the low multipliers. As we exceed 400MHz by any substantial amount we must continually raise voltage, increase timings, and/or reduce the level of PAT-like enhancements. This means that precious little improvement in the memory performance for clocking the memory in excess of 400MHz.

The only other thing we can do is use the async memory modes, most commonly the 5:4. But this tends to be harder yet on the memory, again making the load that double sided dimms or 4 singles places on the address bus hard to deal with at elevated fsb. So in the end if you can use double sided dimms or 4 singles and achieve enough fsb and tight timings simultaneously, by all means do it. This is the path I've take with my personal machine, as my cpu's 18x multiplier means I don't even reach 400MHz on the ram. And the performance yielded (1.99 hour SETI time, 10,700+ PCMark, 500+fps Q3) shows that application performance is barely impacted by only running the memory at 380MHz... if we use all the extra capability running the memory slower gives us to implement radically faster latency characteristics through lower memory timings and PAT.

[daos]

i couldn't agree more. my main point was double sided vs single sided always performs better in DDR400 specs.