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Overclocking Core i7 920 3845B to the max

post #1 of 18
1/28/10 at 11:32am
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First I had 3913B which OCed to 4.2 with 1.38v vcore Prime95 Small FTT Stable (blend test resulted in workers stop coz my RAM seems to be bad!)

Then I found this 3845B baby and bought it immediately and it turned out to be great doing 4030Mhz@1.184v vcore

I need to take it up from there to 4.5+

Which BIOS settings should I use ?

I have Gigabyte EX58-EXTREME and for 4030Mhz I put 192 BCLK with Turbo ON and HT ON with vcore@Normal and DRAM@1.66v and the rest is AUTO
in Easy Tune 6 it shows CPU VTT@1.355v , is that normal ?

My Rig :

Core i7 920 3845B

Gigabyte EX58-EXTREME

OCZ 6GB Platinum 1600 CL7

OCZ Vendetta 2 CPU Cooler (waiting for Megahalems)

Asus HD5870@1000/1300

Antec TPQ 850
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post #2 of 18
1/29/10 at 4:37am
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Hey guys it is my first post here
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post #3 of 18
1/29/10 at 4:38am
Send it too me and I'll run it at 4.5GHz+

Try to incrementally step it up. 4.2Ghz in the 1.225v core @ 200 bclock would be my guess for the next step. At 200 bclock you shouldn't need to up any other voltages. Next to try for 4.4Ghz; @ 210 bclock you will start to need to tweak other voltages besides just Vcore; Vtt (uncore) will have to start to be raised and QPI Vtt also. I'm not too familiar with the exact hardware you list.

I would also relax the timings on your RAM (I try to put in ridiculously slow timings at this stage) so when your testing bclks higher than 200 you can be sure its not your ram causing errors.

Once you find the Vcores and VTT and QPI voltages for 4.2 and 4.4 you have a reference for pushing your chip to the Max. Vcore will probably start to increase exponentially around the 4.5GHz mark and beyond. If you really want to push the chip to the max on air then slap some ultra high CFM fans on that megahalems.

Oh... and if you are able to push beyond 219Bclock you will almost surely need to up your PCI-E past 100. If you really want to push things, I would pull out all the extra devices from your computer that you care about. Soundcards, that 5870 (throw in one of those old GPU's that we all have in the bottom of our desk drawers.) Higher PCI-E freq's have been known to cause issues with other devices and even kill components.

Then once you've figured out the max settings the CPU (and your cooling) can take. Dial in your RAM if you actually even care about RAM speed.

Thats my rough technique, its a balance of patience and 'just going for it'.

GL and HF!
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post #4 of 18
1/30/10 at 3:58am
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Thank you very much for your reply

I managed to run @4.45Ghz with 1.376v vCore

The problem with that speed that my RAM ran @auto voltage which was 1.8v

When I put the RAM at 1.66v the PC won't boot. I know there is a problem with my RAM and will replace them in two days with OCZ Blade DDR3 2000 CL9 but want to know why would the PC runs fine (didn't test stability but ran 3DMark Vantage ang got a score) with RAM@1.8v and wouldn't even boot with 1.66v ? Is there another voltage I can tweak in order to run it @1.66v ?




Another thing :

I managed to boot@4.62Ghz but no stability at all and that was with 1.42v :



What to do next ?

Gigabyte X58 BIOS Settings screenshots would be awesome
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post #5 of 18
1/30/10 at 2:40pm
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How strange !

I put the CPU@4.2 with 1.248v and it could run stable now
The only change I did was to put CPU Vtt @1.175v (Default-Normal) instead of previous 1.355v(Auto)

It seems to me that higher voltages affects stability the same way as lower voltages for the Core i7

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post #6 of 18
1/30/10 at 2:43pm
Nope, your chip just doesn't like higher voltages. I have the same stepping for my Xeon and it just does not like high VTT (no matter what).

Have you made sure to run your uncore frequency at twice your memory speed?

Edit: Why are you using E-LEET on a Gigabyte motherboard. Ahahah

Get CPU-Z mate.
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post #7 of 18
1/30/10 at 3:05pm
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Strange

Would that be a limiting factor for overclocking to the max ?

With my previos Asus P6T and previous 3913B Core i7 920 I had to put both CPU Vcore and QPI/DRAM (Same as Vtt I presume !) at 1.381v

The Uncore is @16X (3200) and I've learnt that the hard way because Gigabyte mobo seems to put it @18X (Memory @8X)

I use E-LEET becuse it has a tab for temps

And I do have CPU-Z but prefer E-LEET

What do you suggest for stable 4.5Ghz OC ?
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post #8 of 18
1/30/10 at 3:07pm
4.2 Ghz @ 1.248V idle, same as how I have my chip running, nice. Some ram just doesn't like to be overclocked much, if it won't post at 1.66V you probably have to loosen up the timings.
BTW cpu vtt has to be within .5V of vdimm voltage, if you are running the memory at 1.8V you want the QPI at least 1.3V to prevent damaging the IMC.
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post #9 of 18
1/30/10 at 4:13pm
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Quote:
Originally Posted by FtW 420 View Post
4.2 Ghz @ 1.248V idle, same as how I have my chip running, nice. Some ram just doesn't like to be overclocked much, if it won't post at 1.66V you probably have to loosen up the timings.
BTW cpu vtt has to be within .5V of vdimm voltage, if you are running the memory at 1.8V you want the QPI at least 1.3V to prevent damaging the IMC.
Load actually



Dynamic VID is awesome
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post #10 of 18
1/30/10 at 4:50pm
I idle at 1.248, load at 1.216.
For 4.5 ghz with ud5 motherboard I set vcore in bios at 1.475, qpi @ 1.28, IOH @ 1.2, ram depends on the timings I use.
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