FSB:DRAM questions

[spoiledmilk]

I have my e6400 slightly overclocked on a ds3 @ 2.56ghz
fsb: 320mhz
bus: 1280mhz

the memory is corsair XMS 4-4-4 12 ddr2 800
what is a better setup:
running it at fsb : Dram 4:5
400mhz
4-4-4-12

or

2:3
with slightly overclocked ram and 5-5-5 15 timings

what is the point of 1:1?

 

[gobucks]

technically, running your memory at 1:1 provides the best bandwith because the bus is running in sync with the RAM. when you run a divider, you're banking on the fact that there will be a substantial portion of the time where the memory doesn't need access to the system bus, and it can just do its own thing. personally, i got better results using a 4:5 divider and 5-5-5-12 timings than i did with a 1:1 divider and 4-4-4-10 timings. specifically, i shaved about 8 seconds off of my superpi 8M time. If i'm thinking of how timings work correctly, then the actual delay of CAS 4 @ DDR2-800 is exactly the same as that of CAS 5 DDR2-1000, since it's the # of cycles / clock speed. so basically timings are exactly the same, but you get free bandwidth.

Also, you can probably get more aggressive with your timings. My corsair TWIN2X-2048-6400 kit has rated 5-5-5-12 timings, but it is perfectly stable at 4-4-4-10 @ 800MHz with 2.1V VDIMM. I also got it to 5-4-5-10 @ 963MHz, 2.1V VDIMM. I bet your sticks can do even better. You may even be able to get 4-4-4-10 @ 960MHz!

 

[spoiledmilk]

thanks, ill give it a shot:
at the moment im running at 3ghz
1:1
5-5-5-15
380mhz fsb

im going to lower the timings