Intel i7 920 (C0/C1, 4) stable at 3.8 ghz and stuck. No more?

Keth

Keth

Keth

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After weeks of trying and starting as a beginner in overclocking, I finally managed to overclock my i7 920 (C0/C1, Stepping: 4) to 3.8 ghz (19x200)

Few points (reasons) why I'm stuck and cannot go for 4.0 GHz:
  1. Whenever I increase BCLK by 1 the whole systems gets unstable (freezes when system is booting up)
  2. On multipler 20 (instead of 19) I never can get stable settings above 3.2 ghz. Motherboard limit?
  3. Whenever I increase cpu voltage by 0.0125v the whole system gets unstable (freezes when system is booting up)

Any solution or ideas?

PC Specs:
CPU: Intel Core i7 920 (C0/C1, Stepping: 4)
Ram: 6GB (3x2gb) Corsair 1333MHz (TR3X6G1333C9)
Motherboard: Asus P6T (Non-deluxe)
Power Supply: Tagan TG900-BZ (900W)
Graphic Card: XFX GTX295 (1792 MB)
Cooling System: Thermaltake, CPU water block, 240x120 radiator (dual-fan)

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BIOS Settings:
CPU Ratio: 19 (fixed)
BCLK Frequency: 200
PCIE Frequency: 100
DRAM Frequency: 1200 MHz
UCLK Frequency: DRAM*2 (2400 MHz)
QPU Link Data Rate: Lowest (~7.6 GHz)

CPU Voltage: 1.40v (I know it's a lot but as far as I know C0/C1 requires more voltage than D0, whenever I decrease the voltage it's unstable)
CPU PLL Voltage: 1.80v
DRAM Bus Voltage: 1.66v
HT (Hyper-threading): OFF
Turbo and stepping: OFF
Rest settings AUTO



Above BIOS settings are stable for over 6 hours (and more) in Prime95.
Is there any way I might go for 4.0 GHz or above? What's the problem I'm not able to overclock more? Is it the motherboard or my cpu revision/stepping limit?

Thank you for reading,
~Keth
 
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Temperatures? Chips run faster at lower voltage if you can keep them cool, and thermaltake do not have a good name

3.8 may well be the chips limit under current cooling I'm afraid. I don't have an i7 (yet), but I believe the D0 ones hitting 4ghz comfortably rather surprised people
 
Think you've got a bit of a duff chip there mate. My C0 runs 3.8ghz with only 1.35vCore and HT stays on. Have you turned Turbo Mode off? I find this makes my overclock very unstable.

I can't get mine to boot full stop at 4ghz though, similar to the problem you're having. C0s just aren't quite as uber as the D0s.
 
reflux said:
Think you've got a bit of a duff chip there mate. My C0 runs 3.8ghz with only 1.35vCore and HT stays on. Have you turned Turbo Mode off? I find this makes my overclock very unstable.

I can't get mine to boot full stop at 4ghz though, similar to the problem you're having. C0s just aren't quite as uber as the D0s.
Click to expand...

Temps below 70 (maximum 75).
Turbo Mode and Stepping is OFF.

C0/C1's are powerful in my opinion. Look at this:
http://www.xtremesystems.org/forums/showthread.php?t=213105
There are like 50 different people with C0/C1 (stepping 4) at 4 ghz or even 4.6 ghz using different voltages from each other.

I think cpu voltage is not depended on revision or model of the cpu.

I think it's my motherboard (Asus P6T) problem which I plan upgrading to EVGA X58.
The reason I think it's motherboard is because x20 multipler is always unstable.

1.35v works for you, not for me - same revision, same stepping, same mobo, probably same bios settings.
 
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I think the D0 chips are very well known for clocking higher than the C1 chips at lower voltage, with the side effect of running hotter.

Every chip is different. Every board is different. At it's most basic, you make a chip by carefully spraying dope onto silicon then sticking it in an oven for several hours. It's not so precise. Your motherboard may well be the problem, but it's also likely to be your chip. The astonishingly expensive classified will help, but even that won't get you 4ghz if your chip wont do it.

20x multiplier gives a fair few people problems, OCZ forums recommended using 19 or 21 as 20 was more hassle than it's worth. Doesn't mean your motherboard is crap.

Finally, lower temps help. A chip will clock higher at 40 degrees than it will at 70, under the same voltage, even though both are 'safe' temperatures. That's just how silicon works. Hence the TRUE, water cooling, peltiers and phase. How long have you spent tweaking this? Overclocking can take quite a while
 
Try increasing by more than 1, in case your CPU just doesn't happen to like that... there's still plenty of board/chip combinations which will produce something of a frequency hole

You may also have more luck on 18x211+ to push it up, if your memory is up to it. Some chips prefer a higher multi and lower bclk, others the reverse is true.
 
my core i7 is stable on x19 multiplier, 20 and 21 are just abit iffy. 21 is alrite for benchmarks but blue screens within ten mins on prime. Try a lot higher bck but put your memory multiplier down one to see if its your memory causing the BSOD's.

Also, disable clock skew, pcie skew, and delay them by 100ps. that made a fair difference to me.
 
Thanks everyone. I will try the suggestions as soon as I will get home.

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reflux said:
Think you've got a bit of a duff chip there mate. My C0 runs 3.8ghz with only 1.35vCore and HT stays on. Have you turned Turbo Mode off? I find this makes my overclock very unstable.

I can't get mine to boot full stop at 4ghz though, similar to the problem you're having. C0s just aren't quite as uber as the D0s.
Signature: Core I7 920 @ 3.8GHZ, 6GB OCZ DDR3, Asus P6T, GeForce GTX 260 GS
Click to expand...

It seems that we have same revision, model and motherboard. Could you tell me what CPU multipler and BCLK do you use? It will help me to determine if it's motherboard limit (multipler of 20).

One more question to everyone:
Can it be my RAM fault because it's only 1333MHz? I see everyone has 1666MHz rams.
I'm not sure if I should replace my motherboard to EVGA X58, my RAMs to 1666MHz or even get i7 940.
Anyone could help me determine where the problem is?

Edit: I just noticed that in first post I've said multipler 20 instead of 19.
 
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I can get mine to 4.0 stable but tbh, it doesn't help anything. I get just as fast load speeds etc, at 3.8. Plus the chip runs cooler there. While the extra 200mhz does give you a larger e-peen, it won't make your games run faster or better. I actually read somewhere that after 3.2ghz, you have to have greater increase to equate to any performance gain, and the gains are more minimal.

I got to 4.0 on my chip with the following settings (granted they may not help you due to differences in specs but) 21x multi, HT on, Speedstep off, 190 bclk, vcore 1.3. Ram volts are at 1.65.

What may help you:
I was told only the ud5, and another board I can't recall, can have a bclk over 200, so you will not be able to have over 200 on yours, and I can't on mine either.

Tbh, if your stable at 3.8 with a 200 bclk that means your ram is running at 1600mhz. Turn your ht on, and your rig shoul fly as is at the 3.8.

I feel pretty lucky because I can do 3.8 stable with a vcore of 1.2 on my chip. Surely having 1.4v on yours is really heating your chip up is it not?
 
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I tried all the solutions above (disabling clock skew, adding 100ps delay, etc), no result.
I guess I will just stay with 3.8 GHz (19 x 200) at 1.40v.

p.s. when HT (Hyper-threading) is turned on I get red lamps on Prime95 after 1 hour (fatal error: 0.4 expected less than 0.5).
 
Edit: Sorry about double post. It's too late now.

Ninja Please! said:
Tbh, if your stable at 3.8 with a 200 bclk that means your ram is running at 1600mhz. Turn your ht on, and your rig shoul fly as is at the 3.8.
Click to expand...

Rams 1200 MHz because I have 1333 MHz rams.

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Ninja Please! said:
I feel pretty lucky because I can do 3.8 stable with a vcore of 1.2 on my chip. Surely having 1.4v on yours is really heating your chip up is it not?
Click to expand...

Temperatuers idle 30-40C, in stress below 70c (75c max)
 
I managed to get into the system with 4 ghz (20x200) with 1.45v (below that, it won't boot).

Prime95:
1.45v< = no boot
1.45v = 1 minute stable
1.46v = 4 minutes stable
1.47v = 9 minutes stable
1.48v = 16 minutes stable (tested twice)

Shall I go for more voltage or is it unsafe? I get temps around 75C.
I've never seen anyone above 1.45v with just 4.0 GHz.
 
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