Help Overclocking E6750 (650i Chipset)

[[R4A]Bigman]

Hi there,
I'm having some trouble overclocking my E6750 - the best I've managed so far, which seemed relatively stable, is 3.2GHz. This is slightly disappointing as I was hoping to hit at least 3.4GHz. My hardware:

C2D E6750 (Step B, Rev G0)
Gigabyte GA-N650SLI-DS4 Motherboard (F7 Bios)
2x 1GB OCZ Reaper PC6400 RAM
Thermalright XP120 + Noiseblocker 120mm SX1 Fan

First of all I dropped the multiplier and pushed the RAM to find its limit. The best I achieved was:
424Mhz (848DDR) 4-5-5-15 2T, 2.2V (Northbridge +0.2V, FSB +0.2V)

Whilst I found this slightly disappointing, it's not all that bad.


Then I held the RAM at 800 (or less) whilst pushing up the CPU speed. At stock voltages, I managed to get to 3.1GHz (8 x 387.9) then had to push the voltages hard to get 3.2GHz (8 x 400):
NB +0.3V, FSB +0.3V, SB +0.3V, VCC12 +0.2V, CPU 1.55V (read as 1.504V)

I've also tried turning the various speedstepping things off and on, but that doesn't seem to make much difference. I also dropped the LDT to 4x to hit those speeds.


At the current CPU overclock I don't even need to push my RAM at all, so that disappointing first RAM go was not even needed! I'm sure I'm missing something fairly crucial here, so any comments or suggestions are really appreciated.


Oh also, I tried to push it to 3.3GHz (8 x 413), syncing the RAM and also having the RAM at stock. I had all the voltages on the mobo maxed out, and the CPU at 1.5875V and it still wouldn't boot.

[Clunk]

It's most likely your RAM that is stretched to it's limit.

[[R4A]Bigman]

But my RAM is still running at 400MHz (stock), and I can't push the CPU any further? Surely the RAM shouldn't be affecting the equation when I'm playing with it like that?

[Clunk]

Didnt realise you were doing the unlinked thing.

Ok, well a few things to double check.

Latest BIOS?
Latest chipset drivers?

There may be some settings that you can take from this guide.

[[R4A]Bigman]

Latest BIOS - check

Latest Chipset drivers - nope going to get them now. Though as I can't even get the damned thing to post after 3.2GHz, I don't think this is going to benefit me massively.

Also ta for that guide - I'll see if I can find anything of note I might have missed from it.

[Clunk]

No doubt there will be someone along that can shed some more light

[[R4A]Bigman]

Ah ha - it appears I met with a 'memory hole'. For some reason it didn't want to be around the 410-415 mark.

I've now it running at 3.6GHz initially stable (8 x 450) - can't quite get it to stay stable under Orthos at 3.67GHz (8 x 460) even with a pile of extra volts.

I think I will work at 3.6GHz and try to bring the voltages down as far as they will go to keep this thing cooler and quieter. Then tighten the timings as much as possible on the RAM to squeeze every last drop of performance out of it

Thanks for the helps

[BUFF]

Ah ha - it appears I met with a 'memory hole'. For some reason it didn't want to be around the 410-415 mark.

could be as 650i has lots of them but it could also be running into internal latencies, iirc there is a strap change on 650i ~425fsb.

[[R4A]Bigman]

Interesting - do you have anywhere where I can find out more about where these strap changes might occur?

[[R4A]Bigman]

Well - I've managed to get it stable at 3.4GHz at 1.425V under Orthos for 12 hours. Interestingly, though, when I stopped Orthos and went away from my computer for a while (i.e. left it in idle) it at some point turned itself off.

Any idea what might be causing this type of behaviour?