How to Set Memory Timings in BIOS

[bloodandsoil]

RAM: Crucial Ballistix PC2-6400, 4-4-4-12, 2.2V
Motherboard: Asus P5B-Deluxe
CPU: Core 2 Duo E6600 2.4 GHz

In my BIOS, when I switch SPD from Auto to Manual, here are the values presented:

DRAM CAS# Latency = 5
DRAM RAS# to CAS# Delay = 6 DRAM Clocks
DRAM RAS# Precharge = 6 DRAM Clocks
DRAM RAS# Activate to Precharge = 15 DRAM Clocks
DRAM Write Recovery Time = 6 DRAM Clocks
DRAM TRFC = 42 DRAM Clocks
DRAM TRRD = 10
Rank Write to Read Delay = 10
Read to Precharge Delay = 11
Write to Precharge Delay = 10

I'm quite new to all of this. Any help would be appreciated. Thanks.

[bloodandsoil]

I learned on another forum that I should set the first four settings, in order from the top, to 4, 4, 4, 12. Like this:

DRAM CAS# Latency = 4
DRAM RAS# to CAS# Delay = 4 DRAM Clocks
DRAM RAS# Precharge = 4 DRAM Clocks
DRAM RAS# Activate to Precharge = 12 DRAM Clocks


But that leaves the remaining 6 settings and I don't know what to set them to. Anyone know? Thanks.

[Fr3ak]

Basically you leave the rest like it is. To fine tune those is kind of hard without the right knowledge.
Maybe have a loot at memset screenshots of other people and try their values. But if you are not benching, you will not notice a difference in performance.

[ziddey]

are you overclocking? I'm assuming you'll be at 400fsb, either 8x or 9x.

In either case, you can run 800mhz ram 1:1.

If you want, you can try timings of 4-4-4-4-4-20-3-9-4-10 and see if that works. If so, with 2.2v, then great!

If not, try 4-4-4-10-4-25-3-9-4-11. If no go, you can try 30-4-10-5-11, and so on, and then tweak down as much as possible if you'd like, and see if it improves.

[bloodandsoil]

Anyone else agree with ziddey's numbers?

[rick_fx]

Anyone else agree with ziddey's numbers?
I agree with Fr3ak. The sub-timings give no noticeable performance difference, except in benchmarks.


But that leaves the remaining 6 settings and I don't know what to set them to. Anyone know? Thanks.
I can't tell you exactly what to set the sub-timings to, but I can tell what sub-timing settings NOT to use :)

"Read to Precharge Delay" under 4 = no boot

"Rank Write to Read Delay and "Write to Precharge Delay" any lower than 9 also = no boot

[ziddey]

Anyone else agree with ziddey's numbers?

if you're looking for loose subtimings to allow you to see how far you can overclock your ram, you could always try 10-15-10-15. However, as far as tightening them goes, I've had sticks have spd programming for slower frequencies (tighter timings) at 3-9-4-11, and then loosen to 4-10-5-12, and further forth. I've personally found 3-9-4-10 to be the tightest I could run on my system. If you think I'm giving foul numbers to ruin your life, don't listen to me. But if you're wanting tight as possible results, give the numbers I listed a shot and work from there. I give those as suggestions since, as mentioned, tighter isn't always better for subtimings, so hopefully those numbers have something in them in terms of not having latency in one particular field too low such that it'd have to go through another cycle to hit.

edit: FWIW, if I leave my sticks at spd and run 550mhz, I get subtimings (asus order) of 4-11-5-14.