v7guy

I've got my system up to a bit over 4ghz and I'm having problems passing prime 95. OCCT, memtest both pass with flying colors, never a problem.

vcore is 1.33750 actual is 1.32 I've done the pencil mod
vdimm is at 2.15
vMCH is 1.30

nforce SPP is at 1.45 I see a few of you up this, why? what is it for?

I'm running 9x 445,
unlinked ram at 445 with 4 4 4 12 timings and all the adv memory settings are on auto...
tRRD 4
tRC 26
tWR 6
tWTR 9
tREF 7.8 uS

what are these for?

I'll take screen shots if someone wants them and will tell me how to.

at rest and light use I see 31C and at full use I've seen a max of 51C
it seems like uping the vMCH has done the most to increase stability but I'm not sure how much higher I can go.


Any suggestions or answers are appreciated.

ericeod

What setting in your bios is listed as vMCH? vMCH is the NB designation for the bios setting relating to the Intel NB chipset. The voltage settings are SPP (which is your northbridge), ram voltage, CPU FSB Voltage, N200 and GTL. People run 1.45v to the SPP because the northbridge needs more voltage to run a higher FSB.

I think you are having an issue because your SPP voltage is too low. Try 1.4v, and if that doesnt work, try 1.45v.


Here is the reference 750i chipset (note that the 750i FTW has full 16x to both cards from the n200 PCI-E 2.0 chip):

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eVGA 680i Overclocking guide .......... ASUS P5E/Maximus Thread.......... 4.4GHz CPU-Z

zomgiwin

bump your voltage up a notch
stay under 1.365 tho and your set buddy!

fraudbrand

Have you tried running it with the memory linked at 1:1 ? That helped me keep my Q9300stable at 3.3 on that board.

v7guy

I'm running the latest BIOS, I've only been doing this for a week (total newb) and I've spent that week reading for hours and hours on here and a few other forums to get to this point. I didn't realize that was a voltage path diagram I was seeing in the 750i FTW thread. I've not ran it at 1:1 because I've seen a lot of people get better results by pushing the RAM harder.
I was using those terms because it's the terms I've been seeing on threads. I had to do more searching to realize what the terms were.

I've actually lowered my CPU voltage today from 1.34375 and found there is no change at all, it fails at the same point in prime95. I'll bump up the FSB and give it another shot when I go to bed. I was just nervous about raising it because it was in the red already and I was having problems finding any info in searches about the FSB voltage. Every time I've bumped up the FSB it's been more and more stable though.

I'd like to bump up the ram more and maybe get more out of the E8400. But I want to get this stable before I continue pushing it.

If there are any more suggestions I'm all ears...

ericeod

I would increase the SPP to 1.4v - 1.45v. The safe setting for FSB voltage for the 45nm dual and quads is below 1.4v. I've OCed E8400s to 4.15GHz+ with only a max of 1.32v FSB Voltage.

__________________
eVGA 680i Overclocking guide .......... ASUS P5E/Maximus Thread.......... 4.4GHz CPU-Z

v7guy

from the tweaking I've been doing it shows that lowering the CPU voltage would help the FSB voltage and an increase in FSB voltage seems to help everything. Accordingly I assume the less cpu voltage I run the better the FSB will respond.
I'll up the FSB and keep the cpu at the same voltage and see how it turns out.

If I can get this 4Ghz setting stable I'll start pushing the ram...

should I start by lowering clock speed or raising the mhz?

flyin15sec

Your RAM may be too tight for over 800mhz. Run the memory unlinked at 800mhz with AUTO for everything in the memory section. At the very least use CAS5 timing 5-5-5-15 2T, if you don't want to use AUTO.

v7guy

I was using 5 5 5 15 2t and everything ran fine at 800 and at 1066.
I tried 4 4 4 12 and occt showed everything fine but prime 95 had problems, I dropped the settings down to 800 and it passed prime 95, i then upped it to 900 and failed quickly. I gave more voltage to the FSB and it lasted longer but didn't pass. I'm currently at the same settings but with more to the FSB and less voltage to the CPU. My thinking being that less power consumed by the CPU will help the FSB run better. I don't know that this is the case, but it makes since to me given the diagram.

Everything passes OCCT, mem test etc before I try prime95.


I'll update when I get up...

Thanks for the input guys
as always all suggestions are appreciated...
if you want screen shots tell me how and I'll post them up.

GeforceGTS

So from what you say in your fiirst post you're running the Doms at 4-4-4-12 890Mhz?

Like others have said, just set your RAM to stock and work on that later untill you have a stable OC on your CPU, another thing, i've found to get better results benchmarking with my ram linked and synched at 875mhz, 4-4-4-12 compared to higher Mhz at 5-5-5-15. Apparently Nvidia chipsets like tighter timings more than Mhz.