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Old April 6, 2008, 10:44 PM
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Default Large Increase in vCore From 3.6 - 3.8Ghz

Hi all,
Still playing around with OC'ing my E8400 (trying to go about it "safely"). Anyhow, I've been leaning towards Linking and Synching.
At 3.6 Ghz - vCore @ 1.275v ran Prime 95 Stable for 8hrs, Memtest 3 Cycles - all no errors
However, I have bumped my FSB to 1700 Mhz, again Linked and synch'd (DDR2 running @ 850 Mhz 4-4-4-12 2T @ 2.2v).
vCore @1.3375 Prime95 error at about 15 mnutes in.
I have now got my vCore at 1.350v, been running Prime95 for about 30 minutes so far no errors
Question: Does this Voltage seem rather high for 3.8 Ghz? All comments welcome!
I will attach a pic of results
Attachment 1883

Last edited by rjbarker; September 13, 2008 at 10:29 AM.
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Old April 7, 2008, 04:38 AM
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I don't know if it's the same as 65nm proc but you can go to 1.45v safely. Just keep watching your temp.
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Old April 7, 2008, 05:39 AM
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Yes, that jump in Vcore is normal. You should be able to push to 4.0 GHz. Now I would not go past 1.40V. That's pushing it for 24/7 ops on a 45nm chip.
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Old April 7, 2008, 07:59 AM
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Also note that while your vCore may be set in Bios to 1.3375, look at what is reported back in your screenshot above. 1.296V. Welcome to vDroop.

My system is set in Bios to 1.3875v, but runs at 1.33v under load 24/7 folding.
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Old April 7, 2008, 08:52 AM
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Thanks folks,
Well, at 3.8 Ghz - vCore @ 1.350, my results:

Prime 95 Small FTT - ran 2.5 Hrs "no errors"
Prime 95 Blended - One Core ran 8 Hrs "no errors"
- Two Core ran 40 minutes "error"

Memory:
Running Linked n Synch'ed (1:1) @ 850 Mhz 4-4-4-12 2T @ 2.2v

Tells me this is a Memory related issue.
Ran this Memory through Memtest 3 Cycles at 3.6 OC - no errors and it ran through Prime 95 Blended for 8 hrs "no errors"

Therefor:
1. Could try it with Timings loosened off to 5-5-5-15
2. Could possibly leave Timings and bump up vCore a notch (between 1.350 and 1.3750). - although I'm reluctant to go with this as Prime 95 Small FTT was fine!
All input welcome!

Anyhow, looks like I'm going to be running 24/7 with 3.6 Mhz!
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Old April 7, 2008, 09:18 AM
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Quote:
Originally Posted by SugarJ View Post
Also note that while your vCore may be set in Bios to 1.3375, look at what is reported back in your screenshot above. 1.296V. Welcome to vDroop.
that is not vDROOP...vDROOP is the vCORE drooping under load, not from what is set in the BIOS. that is simply the BIOS not setting the voltage that is selected. some call it vDROP (one O) when actual voltage is less than BIOS set. so again...

vDROOP = difference between idle and load voltages...has nothing to do with what is set in the BIOS. HTH

as for the OP, at some point, every CPU stops gaining significantly from voltage. 1.3v @ 3.8GHz isn't bad. i have an E8400 that is 4.1GHz stable at 1.30v (actual under load) but it took many many to get this one.


***ahhh, there we go...this is vDROOP

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Old April 7, 2008, 11:25 AM
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Thanks 3oh6, but that's exactly what I was trying to say.

His system is under load, check his screenie. Running Prime95.

Maybe I should have taken the time to outline both vDrop and vDroop as you did. I know I experience a lot of both with my board.


RJ - try unlinking your memory speed. Leave it at 800 or 850. Then boost your FSB, try it again. You may be running into the same wall I did when I had DDR2-800 memory. You can probably get past this with the unlinked memory available with the Nvidia chipset. I had to get new memory. Find your max CPU overclock, then muck with the memory.

PS - how was movie night? I hope you bought her some popcorn.
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Old April 7, 2008, 11:45 AM
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Thanks guys,
I will try "unlinking Memory" and setting to 800 Mhz, although I would like to try the same "run" and perhaps loosening my Timings slightly? to 5-5-5-15?
Here is where my vCore stand so far:

3.4 Ghz Stable @ 1.125v (Memory unlinked 800 Mhz 4-4-4-12 1T @ 2.125v)
3.6 Ghz Stable @ 1.275v (Memory unlinked & Linked / Synch'ed 800 Mhz 4-4-4-12 2T @ 2.125v)

*3.8 Ghz unstable @ 1.350v (Memory Linked / Synch'ed 850 Mhz 4-4-4-12 2T @ 2.2v)
* this is why I'm wondering if (before unlinking) I should try loosening Timings to 5-5-5-15 ?
I have run this Crucial Ballistix Tracer thru Memtest (windowed vesrion) 3 cycles with the 3.6 OC with no errors. the first time I tried 3.6OC I left the Memory at Copmmand Rate 1T and got an error running Memtest, this was "solved" by changing the Command Rate to 2T.

BTW, I was told (after all this playing around with my new Rig), that I need to shave, shower and get out of my sweat-pants , I didn't think it was that bad, until she advised that perhaps "lancing" my sores might be a good idea!!

Thaks guys!
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Old April 7, 2008, 05:06 PM
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You may be able to loosen timings on your mem and get it to work. You may also try raising your memory voltage.

The reason I suggest unlinking is so you're not changing 2 things at once. FSB and memory speed. You know it works at 800, it should work at 850, it may work at 900 but maybe not.

Try your CPU at 3.8Ghz with the memory at stock speeds/timings. I bet it will work if the CPU is getting over 1.3V at load.
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Old April 7, 2008, 05:20 PM
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Does anyone know if those bios voltages are calibrated at the manufacturer? Or is it just a 'hopeful' voltage setting? I do not trust this number, nor do I trust any software readout including of course CPU-Z. It is a good indication of rise and fall relative to the previous value, but that's about it. How do we measure the actual voltage to the processor? Anyone ever tried?

I'm curious because I've pushed my BE to 1.55V, I run daily at 1.45, I would love to actually measure it with my calibrated DMM to see how true the readouts are.

I would imagine every motherboard will be off by 1-5%, depending on the specific manufacturer's tolerances.
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