Normal Voltage for E6750

[Ken429]

I am about to buy another EP45-UD3P MB for an "old" E6750 cpu that is currently installed on a now defunct abit IP35 Pro MB. I have always been concerned about how hot the cpu gets when OC'ed beyound 3.2GHz. Now I think I know - the abit is defaulting to 1.35V. That's as low as the BIOS will allow. It looks like the E6750 wants only 1.18V to run at stock! Will the EP45-UD3P board give it less voltage as a default and let me increase as needed?

[Chike]

Re: Normal Voltage for E6750

1.18 is the default value in BIOS?
Make a registers text report with CPU-Z(click "About", click "Save Report (.TXT)" and see what Max VID is.
For OC more than default is likely needed.

[Ken429]

Re: Normal Voltage for E6750

Learned a new trick - thanks. CPUZ64 says the Max VID is 1.35V. So that means the abit BIOS is setting the starting "Default" voltage at the MAX! Will the Gigabyte board set up at the default VID of 1.18V and let me play with the voltages as needed. Seems like 1.35V is very high for 3.2GHz 24X7 usage - my Q9550 will run at 4 GHz at 1.35V. Any input on how much I can expect from the E6750 on the Gigabyte board. I would use the 4X1GB sticks of Corsair DDR2 800 C4 memory.

[Chike]

Re: Normal Voltage for E6750

Max VID in CPU-Z is max vcore for the processor at it's max stock speed.
Max VID for the E6750 is 1.5v.
The Q9550 is a newer 45nm processor which is different from the 65nm E6750 processor. BTW which stepping is your Q9550 C1 or E0?
What is core voltage reading in CPU-Z under load like Prime95 for the E6750?

[Ken429]

Re: Normal Voltage for E6750

OCCT says the Vcore is 1.18v when idle and 1.30-1.32V when the E6750 is under load (400FSB * 8 =3.2GHz). The Q9550 is E0 stepping and runs at 1.31V when idle and 1.265-1.28V under load (450FSB * 8.5 = 3.825GHz LLC Disabled). Strange, the BIOS on the abit board does about the exact opposite of the BIOS on the Gigabyte board. Back to my original question - should I buy the Gigabyte board and be able to run the E6750 at a lower Vcore and/or get a higher GHz with less heat? Just in case your going to ask, I have a whole box full of Zalman cpu coolers in every shape and size so I am not using the Intel stock cooler.

[Chike]

Re: Normal Voltage for E6750

I can't answer your original quetion, I don't know how high the E6750 will OC and with what voltages and temperatures.

For the E6750 do you manually set voltages or do you use C.I.A. 2/auto settings? Do you use the same method for both processors?

How hot does the E6750 get (core/CPU temps)?

[Ken429]

Re: Normal Voltage for E6750

Oh well, for $100 I'll by another EP45-UD3P and let you know how it turns out.

[profJim]

Re: Normal Voltage for E6750

Your E6750 is similar to my E6550.
The highest stable o/c with my cpu is 494 x 7 = 3.458GHz, with CPU Vcore = 1.36875.
With your 8x cpu multiplier, you should be able to o/c to 3.90GHz or higher.
I could run stability tests up to 528 x 7 = 3.696GHz, but my setup was never completely stable with FSB = 495MHz or higher. YMMV.

Temperatures with my system are very good, see my signature.

[Ken429]

Re: Normal Voltage for E6750

ProfJim - good to see your still on duty. I thought I would give "our" Q9950 system a rest and play with the E6750 system for awhile. I was surprised to see that the abit BIOS (CPUz64) shows 1.18V when E6750 is idle and jumps up to 1.32V under load (400 FSB * 8 = 3.2GHz). But... the temp also jumps up from 30C when idle to 54C under load. I have a Zalman CPNS 9500 on this thing in an all aluminum Lian Li PC60 case. I can see another Corsair H50 cooler on the horizon! Based on your stuff and the Max VID it looks like 1.35V is not out of line for this processor. I don't think the abit versus Gigabyte MB will make it run any cooler but I was trying to rationalize a new MB anyway since abit is no longer in business and W7 drivers for their OC'ing software does not exist. So...by next week I should have a EP45 UD3P MB and I'll probably be looking for some more help.

[profJim]

I was surprised to see that the abit BIOS (CPUz64) shows 1.18V when E6750 is idle and jumps up to 1.32V under load (400 FSB * 8 = 3.2GHz).

It sounds like your Abit bios had EIST and C1E enabled for power saving. With these enabled, your cpu idle voltage and core speed will be reduced. Both of these will increase to the standard values when your system is under higher loads.

Your core temperatures sound about right. With a decent air cooling setup, core temperatures will rise to about 50 (C) when running Prime95 or OCCT. Running IBT or LinX will raise core temperatures another 10+ degrees.

As I recall, most of the original Core2Duo e6xxx processors had a stock VID in the 1.35 volt range.

Good luck with your new mobo, we're here to help you with your overclock.

[Ken429]

Re: Normal Voltage for E6750

ProJim, Back to the Q9550 system - I backed it off the FSB to 450 and lowered the Vcore to 1.34375V (LLC Disabled) and ran Prime95 for 6 hours. The voltage that OCCT showed using the above settings was 1.31V at idle and 1.26-1.28 under load. I then Enabled CIE, EIST, and Virtualization and walked away thinking all was ok. After this E6750 discussion I went back and ran OCCT on the Q9550 with the Enabled C1E and EIST settings and it now shows the system is at 1.07V when idle and at 1.20-1.22 under load. Does the 1.20-1.22V make sense, the Vcore is still at 1.34375V? The system seems stable but I have not run Prime95 - I think I'm afraid to??!!

[profJim]

Re: Normal Voltage for E6750

I'm not sure why you're afraid to stress your system using Prime95.
The worst that will happen is that your system will crash and "burn".
You might get some file corruption when this happens, but it's really a non-issue if you have a backup image of your boot partition where you can quickly and easily restore the boot partition.

I went back and ran OCCT on the Q9550 with the Enabled C1E and EIST settings and it now shows the system is at 1.07V when idle and at 1.20-1.22 under load.

It's not clear which OCCT test you ran and for how long. Were you running any other monitoring programs that display voltages and the cpu load for all cores?
Windows Task Manager (Performance tab) will show you how heavily loaded each core is during the test.

With LLC, EIST, and C1E disabled, your cpu voltages have the expected vdroop of about 0.06 volts.
With EIST and C1E enabled and with a consistent 100% load, your cpu voltage should be similar to your results with EIST and C1E disabled.

I suggest testing your Q9550 by running a quick 10 loop test using Intel BurnTest (IBT) or LinX using the maximum amount of available memory. Either of these tests will result in cpu core temperatures that will be 10+ degrees higher than when running Prime95 or OCCT stress tests.
I have never run either of these for longer than 20 loops.

Another excellent test is to run OCCT PSU test, which stresses your cpu and graphics card at the same time. Even though OCCT can display and save graphs of voltages and temperatures, I run cpu-z and RealTemp while I'm testing my system.

If you're anal (like me) when it comes to stress testing, I run each of the three Prime95 or OCCT tests for 24 hours each when I've reached my "final" overclock.
I cheat a bit and only run multiple 12 hour stress tests when I'm in the process of seeking my overclocking goals.

[Ken429]

Re: Normal Voltage for E6750

The "afraid to run Prime95" was my sad attempt at humor since I new it would fail. Prime95 ran for less than 1 hour before W7 rebooted. I'm really confused now since the system was stable with C1E and EIST Disabled. I then increased the Vcore from the 1.34375V to 1.36250V and now OCCT and CPUz64 say the cpu voltage at idle is 1.30-1.33V and 1.28-1.30V under load. That is with C1E and EIST Enabled. It's like the BIOS has had a mood change. What am I missing?

[profJim]

Re: Normal Voltage for E6750

Your Q9550 obviously isn't stable with EIST and C1E enabled.
Which stability tests have you run and for how long with both of these options disabled?

It would be best if you created a new thread where we can take a look/see at what might be causing the problem.
I suggest a title with something like:
Q9550 + EP45-UD3P overclock not stable with EIST & C1E enabled
so that others will we drawn to the new thread.

The best bet will be to post your failed bios settings and include a screen-shot that includes:
Memset using the SPD and ">>" tabs
cpu-z CPU and Mainboard screens (several instances can be run at the same time)
EasyTune6 --> TUNER tab --> ADVANCE tab --> VOLTAGE tab (only the Voltage tab is needed)
CoreTemp screen [for your cpu's VID (Voltage ID)]

Be sure to detail which tests failed, error messages and how long the test ran. It would help if you include the failed Prime95/OCCT or IBT windows that generate errors.

The problem might solved with some minor voltage tweaks and/or reference volt changes.

[Ken429]

Re: Normal Voltage for E6750

You're right. I will start a separate thread. I don't know if it is sun spots or what but I rebooted and the voltages are back to "normal". Honest, I did not change anything. Back to the E6750 discussion!