Overclocking - Memory Query

Gaijin

Gaijin

Gaijin

Soldato
Joined
18 Feb 2003
Posts
8,616
Location
Brighton/West Wicklow
Hi chaps,

I've had a fair degree of success with overclocking my E6600.

Equipment is below:

E6600 Currently at 3.1Ghz on water (344x9)
4GB Corsair DDR2 XMS2 DHX PC2-6400C4DHX TwinX (2x2GB)
Asus P5Q Pro
Enermax 625W Modular PSU
Powercolor 4870X2
Vista X64 Ultimate

Things started to get a bit flaky over 3.4Ghz, and very ropey at 3.6Ghz which was/is my target.

Basically what happened is that I started to get BSOD's around 3.45Ghz, and decided to be a bit gung ho and upped the Vcore and went for a direct 3.6Ghz, which ended up in BSOD's. I wouldn't usually be so ham fisted, but the chip was a hand me down from a friend (for free) and thus i wasnt too bothered about frying it.

So I then backed down the OC to 3.2Ghz and noticed the BSOD's kept happening, so I changed my voltages (which I stupidly hadn't written down at this stage). However, when I removed the clock completely, I was still getting BSOD's.

I basically attributed the BSOD's to a stuffed Windows install and thus reinstalled windows. Sure enough I was able to clock again without the BSOD's.

However, without my old voltage settings i'm effectively having to start again with the OC.

As I mentioned before, its currently at 3.1Ghz due to the time overclocking takes, and the desire to play the backlog of games I have ;) but I've had it running reasonably stable up to 3.4Ghz. However, i've noticed that with the memory divider set to auto, I either get very low memory speeds (which the BIOS says will cause instability) or very high speeds (have seen 933Mhz at one point). I understand that this is due to the memory not running 1:1 which it would at 3.6Ghz, but how dodgy is it to run at speeds away from the spec'd operation speed (I.e. 800Mhz)?

Also, with regards to the memory speeds, to what extent is safe in terms of stability? and is it better to have the RAM underclocked or overclocked, whilst trying to achieve the target/1:1 figure?

Thanks for your help in advance guys, i'll try to post my BIOS settings when I get in.
 
I don't understand people's concern with running 1:1. What's the reason for this?

Your primary concern should be CPU speed, followed by MCH speed / latency, followed by memory speed / latency.

The former is obviously defined by the age old multi and FSB.

MCH is determined by FSB and tRD ("AI Transaction Booster"on the P5Q)

Memory is determined by FSB, divider and timings.


My suggestion would be to drop the memory down to 1:1, slack timings (like 5-5-5-15), highest CPU multi. Drop the "Performance Level" (tRD) down to 10 (this is controlled by the AI Transaction Booster being set to Manual - this is very much like a memory timing - lower = faster).

Find highest CPU speed.

Then move on to finding the highest FSB / lowest tRD by dropping the CPU multi down and upping the FSB / lowering the tRD.

Finally, find the highest memory speed / lowest memory timings.

Once you know how fast each component will go, dial in the sweet spot, remembering that CPU speed is your priority.

There are some excellent articles on Anandtech describing tRD and the tuning of the Core2 Platform.

e.g.

http://www.anandtech.com/mb/showdoc.aspx?i=3208&p=4

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3239

http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3184
 
First of all, thanks for the response Jimbo - appreciate it.

I'm not hung up on the 1:1 at all, I suppose i've heard that it has marginal performance benefit, which makes it a target, but I certainly won't lose sleep over it if I don't achieve it!

What I was really asking is, due to the BIOS stating that running the memory below spec can/will cause instability and the similar impact of running the memory above the rated speeds - how large is the risk of stability either way? and is it safer to run the memory below its rated speed or above it?

Obviously not running 1:1 you are going to get one or the other, so I guess i'm just wondering what is best to remove the RAM as a cause of stability issues in order to get the highest OC.

I've slackened the timings but haven't used the transaction booster - and so i'll give that a try.

If you could answer my questions above, i'd be grateful. Sorry if I've posted anything stupid - it's all a learning curve to me!
 
You must log in or register to reply here.
Back
Top Bottom