pc4000 timings

Hello everyone, Im working on my first OC right now and I was informed that my mobo doesnt like tight RAS to CAS latency so I was advised that I change my timings from 3-3-3-8 to 3-4-4-8. Im lacking in knowledge about timings so could someone tell me if this makes my RAM run at slightly slower speeds? If it does what sped would it be running at? Thanks for any input.

Increasing you timings castrate your memory bandwith. Here's what I found on meh AMD rig...

memtest86 (Single Channel)

BH5 @ 220 (1076MB/s) (2-2-2-11)
Ch5 @ 220 (978MB/S) (2-2-3-11)
PC4k @ 220 (754MB/s) (3-4-4-11)

240 (PC4k) = 220-218 (BH5)

250 = 241 (BH5)

255 (PC4k) = +-250 (BH5)

PC4k moves exponentially, while BH / CH5 is more linear in bandwith. If you can get PC4k to 255-260, it will be equal/faster than BH5 @ 245-250mhz.

However keeping it at the same speed is a *bad* idea if ur gonna increase the latency

So changing my timings from 3-3-3-8 to 3-4-4-8 would be a bad idea? I am aiming for 250 FSB. I was running at 2.5-3-4-6 for a little while and that seemed to work out alright for me. any pointers, heres my current OC: http://www.ocforums.com/showthread.php?s=&threadid=290026

I am aiming for 250 FSB.

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....

However keeping it at the same speed is a *bad* idea if ur gonna increase the latency

Click to expand...

If you are aiming for 250... yes.. but *dont* keep it at the same speed.

all things equal, the slower the timings the slower the memory bw. however, increased cpu speed and fsb speed can more than make up for the slower timings. for example 2-2-2-5 at 225 fsb
is not as dersirable as 250 @3-4-4-8 cause not only are u increasing the fsb but u are increasing the cpu speed substaintially,which will give u better overall performance.

Sentential said:

....If you are aiming for 250... yes.. but *dont* keep it at the same speed.

Click to expand...

I think I need a little verification here So you're saying that if I go for 250 fsb, then changing from 3-3-3-8 to 3-4-4-8 would be a bad idea? What do you mean by dont keep it at the same speed? Sorry for my ignorance, please bear with me on this one

....So you're saying that if I go for 250 fsb, then changing from 3-3-3-8 to 3-4-4-8 would be a bad idea?

Click to expand...

If you're going from 236FSB to 250FSB, you may have to relax the timings to 3-4-4-8 or your memory won't work. If you don't have to relax them, don't; but you probably will.
The tighter the timing (lower numbers) the faster the memory will be, but you usually have to give something up on this end to gain something on the other end. You'll probably give up the tight timings to gain the extra cpu speed and memory bandwidth.

The 2 timing elements that you're changing (RAS# to CAS# Delay and RAS# Precharge) are the ones that make the difference. Changing the CAS# Latency from 2 to 2.5 to 3 and the Cycle Time (Tras) from 5 up to 8 probably won't make any difference in the frame rates you get in games.

great info everyone, thank you very much, i was always a little leary about RAM timings but you really helped me out. thanks a bunch