My humble i7 860 overclock - Can it be improved?

[Trist_58]

GDay Tom's people,

It's taken me about a week but I think I finally know what I'm doing with my BIOS. With my low-end after market cooler installed I have been able to make a half-decent OC on my CPU at 3.6 GHz but it seems I have hit a wall and have not reached my goal of 4.0 GHz. So I thought I would ask the only experts I know and see if you guys can suggest ways to achieve a higher clock speed on my CPU.

Here are my relevant specs and current BIOS settings:

Mobo: Asus P7P55D LE
CPU: i7 860 2.8 @ 3.6 GHz
Heat Sink: Cooler Master Hyper 212 Evo
RAM: 4 x 4GB Princeton Dual channel
GPU: EVGA GTX 580 3GB @ stock

BIOS version: 2003
CPU @ 3600 MHz
DRAM @ 1080 MHz
BCLK: 180
PCIE: 100
QPI: 5766
CPU DIFF AMP: Auto
CPU Clock Skew: Auto
IMC Voltage: 1.3
VCore: 1.23750
DRAM Voltage: 1.5
CPU PLL Voltage: 1.9
PCH Voltage: Auto
DRAM DATA REF Voltage on CHA: Auto
DRAM DATA REF Voltage on CHB: Auto
Load Line Calibration: Enabled
CPU Spread Spectrum: Disabled
PCIE Spread Spectrum: Auto
Hyper Threading: Enabled

- All power saving features disabled.

I hope I haven't left anything out.

Even though I'm using a pretty old i7 I have heard of and was expecting a higher OC, perhaps up to 4 GHz. The main problem I have encountered is the thermal barrier. Prolonged testing with Prime95 at the above settings reached a Max Temp of 85'C so I really don't want to push the VCore any further until I get better fan installed to make a push/pull configuration on my heat sink. I hope this will drop the temps by 5'C.

I guess my question to anyone with the knowledge is are there any tips you can give me to make it possible to push some more speed out of the system?

For example I have read that i7's actually OC better with ODD multipliers so is it worth playing around with that idea?

It may be possible to reach a better CPU clock speed and maintain stability by increasing it's multiplier and lowering the BCLK but will that actually make my system perform any better?

I suspect half my problem is my cheap Hyper 212 Evo not performing like some of the big guns but it's just about the only one that would fit in my case.

Anything else that may help me in my operation would be greatly appreciated, especially from those who have overclocked i7 860's before.

Thanks for reading all this!

 

[Haserath]

Reaching 4Ghz with a 1.23V vcore would be lucky. Are you sure your heatsink is seated correctly with good paste? 85C is pretty high even for a hyper 212; at least, if the 800 series runs like the 900 series, it should since it's practically the same core.

I'm running a 920@3.8 with a 1.27 load Vcore and it's running at or below 72C in a 27C room with the same cooler.

You should try running a lower PLL voltage. 1.8V is stock for that processor; if you can get it lower than that, I would recommend you try for 1.6V. I would also try lowering your IMC voltage.

If you can get those two down, that should bring your temps down.

I would try a 21 multiplier with a 190 base clock when you have enough thermal headroom for a higher Vcore. You should be able to hit 4Ghz with around 1.27-1.3V.

 

[Trist_58]

Hey,

Yeah you're def right about not being able to reach 4GHz with 1.23v VCore so I really hope I can reduce my temps a bit. I was going to remove my heatsink today but I left my thermal paste remover elsewhere so I'll have to leave it for now. I do have AS5 applied.

I have my PLL Voltage at 1.8v currently and I don't think I can lower it any further but I'll have a look. I will try the BCLK at 190 in order to achieve 4GHz with 21 multiplier. Maybe I can exchange some IMC Voltage for a little more Vcore and hopefully get better performance.

Thanks for the tips mate, I hadn't tried it that way before.

Will keep you posted!

 

[Trist_58]

As I thought, I can't set the PLL Voltage to below 1.8 but I did manage to shave 5'C off my CPU temps under load by reducing IMC to 1.2v. This is a good thing but I'm still reluctant to increase the VCore until I get the thing to cool down a bit more.

I know my case air flow is less than ideal but surely the thermal paste must be applied incorrectly? And it's not like it's hot here atm, probably no more than 15'C!

Anyway I should have it sorted by the end of the week so until then I will be refining the BIOS a bit more and probably try not stress the CPU too much. I would like to keep it going for up to another year if that's possible.

Thanks again for your input.

 

[Haserath]

Can you lower the IMC more than that? I looked up the intel docs for that processor, and the IMC voltage is 1.05V at stock.

No problem.

 

[Trist_58]

I'll try IMC with 1.15 and see if it will cope with P95. I thought I had tested this already (where are my notes hehe) but it's worth a shot!

 

[Trist_58]

Unfortunately BCLK at 180 with just 1.15v IMC the CPU didn't make it past 16 minutes of Prime95.

I have just been reading up on how much each part of your overclock actually contributes to overall system performance and it seems (in most games at least) that increasing the frequency of the BCLK in itself doesn't actually make a difference whether it's at 133 or 175. I had been wondering if the BCLK actually does much besides create a balance between the other multipliers so it's nice to have discovered this information.

So with that in mind I think it might be worth lowering the BCLK and IMC voltage a fair bit and then upping CPU multiplier and VCore. I might even reach my 4GHz this way (if I'm lucky).

Thanks for putting me on the right track, Haserath! Anything else you think I've missed?

 

[Haserath]

You're right. The base clock has no impact on performance by itself, but it is the clock that all of the other processor clocks are based upon.

The IMC voltage is the memory controller voltage on the processor. Its stability and voltage will depend on what ram speed you run at.

I can't think of anything else that will bring much of a change. I must've been looking at a different voltage if your IMC voltage can't be lowered that much. Good luck reaching 4Ghz.

 

[Trist_58]

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