Memory Timings Query

Zilla774 · 19 Jan 2006 at 11:32

I have just read the FAQs and another memory timings thread, but rather than hijack any of these I have a few queries based on wanting to improve my timings and performance.

I have a set of Corsair 2GB DDR XMS3500LL Pro TwinX (2x1GB) running in an Asus A8N SLi deluxe with an FX-57

currently I have the system set as follows:

FX-57 - 15x200 - 3GHz
Memory - DDR400
2.5 CAS
6 Tras
3 Trcd
3 Trp
11 Trc
13 Trfc
4 Trwt
3 Twr
1t Timing

System is on Air and is currently stable and not running hot. My questions are:

1) Can I change the memory speed from DDR400 to 433 safely?
2) What can I then change the memory timings to? (and which do I ignore?)
3) do I need to match settings, or change one thing at a time?

these are probably extremely noobish questions, and for that I apologise, but while I've had experience with clocking CPUs and GPUs, I've never ever changed the memory. I'm aware that it will give an increase in performance and would like to squeeze my system a little.

thanks in advance for any answers

smids · 19 Jan 2006 at 12:41

With A64's as you may well know, timings are more important than frequency. If you are changing from 400-433 (200-216mhz) then I would look at what timings might be needed. If it involves a drop below cas 2.5 or should you need to use a TRCD or TRP of 4, then I would say forget it. Only do it if you can reach that with 2.5-3-3-[11] max for example @ 1T.

So answering your question, yes, you can do it safely - though set your CPU to stock first, to get the timings of the RAM right, then clock up again, testing all the way.

.

For info on RAM timings, see my overclocking guide here: http://forums.overclockers.co.uk/showpost.php?p=4886705&postcount=209

Zilla774 · 19 Jan 2006 at 14:09

omg, ok I read the guide, but its all still voodoo. so I think I'll do what I always do:

fiddle until things go horribly wrong, then load the default settings all leave it...

smids · 19 Jan 2006 at 14:14

Basically, underclock your CPU - set 10x multi for example. Then set max mem frequency (divider) to 200mhz/400mhz depending on BIOS. Then raise the FSB to the required memory frequency (as you have set 1:1 FSB:RAM ratio). Then loosen timings, starting with TRAS (up to 11), followed by TRCD (up to 4) followed by TRP (up to 4). If you cannot get stable, 2.5-4-4-11 1T maximum, then don't bother.

Run memtest at each clock and DO NOT load windows under ANY circumstance until the RAM is checked with memtest (to avoid corrupting it).

This may sound like a harsh warning, but don't worry if RAM isn't completely stable and you load windows, but if very unstable, there is a risk of corruption.

Zilla774 · 19 Jan 2006 at 14:32

cool, ok, will do.

it made a big difference changing from 2T to 1T and that's completely stable. I will try getting the CAS from 2.5 to 2 as that should make a difference too? After that, I'll probably leave it, I would rather have a working, if slightly underpowered system, that a broken one

smids · 19 Jan 2006 at 14:42

Zilla774..... what are you like? :rolleyes:

I just did some research on your RAM - it is rated at 433Mhz (216.6Mhz) @ 2-3-2-6 1T (CL-RCD-RP-RAS)

Your suggestion is not overclocking, but merely setting to the rated speed.

It should run fine. Set it to that at the default voltage and run memtest. If it fails, RMA it for not running at specified speeds. :rolleyes:

Zilla774 · 19 Jan 2006 at 14:52

I am like a noob is what I'm like LOL

ok, thats really why I asked as I saw it was specced to run at that. So I'm just gonna set it to that and hope it doesnt fall over LOL

'preciate the help

Jimbo Mahoney · 19 Jan 2006 at 15:41

Just FYI, Trc and Trfc are more stability-oriented than performance.

Tras should be CAS + tRCD + 2 at the least.

Zilla774 · 20 Jan 2006 at 16:10

ah, neat ok

I've pretty much just changed the timing from 2T to 1T right now, I am seeing an improvement from just that and having tweaked other settings for no gain have decided to leave it at that right now. It's not like I have a slow system or anything

Thanks for all the suggestions however

Jimbo Mahoney · 20 Jan 2006 at 19:00

Yeh, CAS and Command Rate / CPC are where it's at.

tRP and tRCD give SMALL gains.

tRAS is more of a stability setting (read up on tRAS violation if you want)

Really, on the AMD64 platform, memory tweaks are icing on the cake, not the cake itself.