Overclocking - Memory problem?

PureAppleJuice · 6 Jun 2006 at 16:42

Hey, my rig is all working now and i've just started to overclock it. Managed to get the Opteron 165 to 2.9ghz fine, however it would seem that I get memory problems in WoW and a couple of other games. Pretty sure it's not my graphics card as it is left untouched.

My spec is;

Opteron 165
Asus A8N-SLi Premium
OCZ 2 x 1 Gb EL DDR PC-3200 Dual Channel Platinum
Antec NeoHE 550watt PSU
7900GT

I know how to overclock the CPU etc. but know sod all about RAM. What do you advise about changing RAM settings to get a stable overclock?

Minstadave · 6 Jun 2006 at 17:20

I take it you're running on a divider already? If you could post a screenshot of CPU-Z's memory tab that would help

First you need to use memtest86+ to see if your memory is erroring. Make a bootable CD with it on and loop test 5 for 5-10 passes and see if you get any errors.

PureAppleJuice · 6 Jun 2006 at 17:23

Newb question coming; what's a divider? I hear the term being mentioned in overclocks and I have rough understanding of memory:fsb ratio.
Will post CPU-Z screenies in a sec.

Do you need details of how the memory acts when it is overclocked? I put it back to normal because of the memory problems I thought I was getting.

vanandjuanunited · 6 Jun 2006 at 17:26

Your memory at stock will run at 200 so set it in bios to run at 166 or 133.

Minstadave · 6 Jun 2006 at 17:29

jidh007 said:
Newb question coming; what's a divider? I hear the term being mentioned in overclocks and I have rough understanding of memory:fsb ratio.
Will post CPU-Z screenies in a sec.

A divider runs your memory at a set ratio of the HTT speed.

If you have your CPU at 300x9 for example, most memory won't do 300Mhz, so you use a divider to run the memory slower.

Most boards describe the memory in terms of mhz, like 100mhz, 133mhz, 166mhz, 200mhz. This isn't actually the speed the memory runs, but the speed at which the memory would be if your HTT was 200mhz.

To work out your memory speed you use (divider speed over 200) x HTT:

So with a 133mhz divider at 300HTT you get:

133/200 x 300

2/3 x300 = 200Mhz

Dividers are great on A64 because it means you can use cheap RAM and not limit your CPU overclock. Due to the large memory bandwidth and onboard memory controller using a RAM divider doesn't incur much of a performance penalty at all on A64 platforms.

I did a quick test of different dividers in this thread (someone was disputing with me about their use):

http://forums.overclockers.co.uk/showthread.php?t=17584377&highlight=dividers+experience

Minstadave · 6 Jun 2006 at 17:31

Yeah in your case with your memory at 200mhz (1:1) you'd be hitting instability quite fast as your memory simply won't be stable at those clocks.

For a simple overclock try using the 133 divider, then you'll be stable to 300HTT without problems, allowing you to really push your CPU.

PureAppleJuice · 6 Jun 2006 at 17:33

Ok thanks. When I was clocking it was set to 'auto'. I'll post some screenies of it when it's clocked, to see if my RAM can be changed anymore.
Will reply soon

PureAppleJuice · 6 Jun 2006 at 17:53

How're those memory timings? Does anything need to be changed?

Edit: Got like tearing in games again from it. It only seems to be when I go beyond 2.7ghz. Temperatures are fine. Any idea?

Minstadave · 6 Jun 2006 at 18:04

jidh007 said:
How're those memory timings? Does anything need to be changed?

Edit: Got like tearing in games again from it. It only seems to be when I go beyond 2.7ghz. Temperatures are fine. Any idea?

Your divider is a bit too low, you want to be aiming for 200Mhz on the RAM, try changing to a 133 divider.

The tearing you describe won't be due to your RAM, sounds like a graphics card problem :confused:

Minstadave · 6 Jun 2006 at 18:05

Your command rate is also set to 2T, you want to change that to 1T to get a nice performance boost.

str · 6 Jun 2006 at 18:14

For a quick test of the HTT stability I would drop the multiplier to 7 and check to see if it's still producing the tearing problem in games. If the problem goes away at 7 x 325 then it's likely the CPU can't handle 2.9Ghz at that Vcore so maybe would need to up it a little to try get it stable.

PureAppleJuice · 6 Jun 2006 at 18:42

Dropped it to x7 no problems. I'm now back on x9 and no problems at all. Do you think changing the RAM voltage would change much? I've just been doing everything at stock, bar CPU.

str · 7 Jun 2006 at 00:58

I just tested increasing the Max Async Latency from 7 ns to 9 ns because I couldn't get stability with 2 x 512MB when running HTT at 350. My setup is stable with 1 x 512MB at HTT 333 and MAL 7 ns but with 2 x 512MB it wouldn't even boot into Windows and would hang in Memtest86+ until I set MAL to 9 ns.

I read it's a useful tweak when running 300+ HTT and it's made a big difference for my setup so maybe it'll be worth trying if you run into anymore memory type problems at high HTT.