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Max safe Voltage for E8500?

H

Hamfiles

Limp Gawd
Joined
Feb 13, 2005
Messages
160
So I was tweaking my Asus P5Q Pro board, and I raised my FSB, so now my E8500 is overclocked to 4.04 GHz (its 3.16 at default speed). I raised my CPU voltage to1.30 volts, but I have a feeling I could get a stable clock of maybe 4.1 or even 4.2 GHz, if I raise the voltage some more.

What is the max safe voltage for the E8500, long term. I mean, if I ran it at 1.5 volts for a year, would this fry the chip?

Also, if anyone here owns an E8500 I would like to know what you have your voltage set to.

Thanks for any replies.
 
The maximum reccomended voltage for a 45nm cpu such as the E8500 is 1.4v, 1.5v would kill it after a while.
 
Thanks.

Well, I would really like to get to 4.2.....maybe i could try 1.45 volts.

What makes this chip so much less tolerant of voltage than my old E4500. I have abused that chip and overvolted the heck out of it, and it still works very well. It ended up in my kids' pc where it is still modestly overclocked.

Anyway, I went over the tolerances for that 65 nm chip, so I was hoping maybe I could do the same with this 45 nm. But I don't intend to upgrade for at least another year, so I don't want to fry this cpu. :(
 
I've been running my E8400 at 8x500 with 1.43v since January 2008 (~17 months). No ill effects and it's still rock stable.
 
What makes this chip so much less tolerant of voltage than my old E4500.


You answered your own question, the internal circuitry in based in 45nm structures and spacing as opposed to 65nm for the 4500. Simplistic anaolgy, bigger wires can carrry more current and the farther apart two wires are the less chance of a short developing between them as they can carry more voltage before a spark will jump.

Not sure the "so much less" is fair, 1.55 (65nm) vs 1.45 (45nm) is a .1/1.55 = 6.45% reduction in voltage (using Intel absolute max Vcc from the datasheets) and if you wish to consider (and we probably should) a possible 50mV voltage spike from the cpu voltage regulation circuity it is then 1.50 1.40 which is .1/1.50 a 6.67% reduction.

65 vs 45 is 20/65 is roughly a 30% reduction in chip size which is huge for improving manufacturing costs and profits. (assuming your yeilds are as good as the previous generation) .
 
Last edited:
hemi said:
I've been running my E8400 at 8x500 with 1.43v since January 2008 (~17 months). No ill effects and it's still rock stable.
Click to expand...

Hey thanks for the reply. Are you using Load Line Calibration enabled (LLC) ?
 
BillParrish said:
What makes this chip so much less tolerant of voltage than my old E4500.


You answered your own question, the internal circuitry in based in 45nm structures and spacing as opposed to 65nm for the 4500. Simplistic anaolgy, bigger wires can carrry more current and the farther apart two wires are the less chance of a short developing between them as they can carry more voltage before a spark will jump.

Not sure the "so much less" is fair, 1.55 (65nm) vs 1.45 (45nm) is a .1/1.55 = 6.45% reduction in voltage (using Intel absolute max Vcc from the datasheets) and if you wish to consider (and we probably should) a possible 50mV voltage spike from the cpu voltage regulation circuity it is then 1.50 1.40 which is .1/1.50 a 6.67% reduction.

65 vs 45 is 20/65 is roughly a 30% reduction in chip size which is huge for improving manufacturing costs and profits. (assuming your yeilds are as good as the previous generation) .
Click to expand...

Thanks for this insight.

On another note, What is your opinion about LLC? Do you have it enabled on your board? I have read conflicting reports about it.
 
Hamfiles said:
Hey thanks for the reply. Are you using Load Line Calibration enabled (LLC) ?
Click to expand...

I'm running it with an Abit IP35 Pro - I think I have it set to 1.45v in the BIOS and it sags to 1.43. I don't remember if the IP35 has a selectable function like LLC. Sorry...been a long time since I set it up. :D
 
Intels spec states the silicon shouldnt be pushed past 1.36V approx.
I've been running also since Jan 2008 at 1.4V, 4.1GHz (E8400).
I would NOT exceed 1.45V.
 
Thanks Nenu.

Well, I just raised the FSB to 430, which is the highest I have ever had it on this board.

I Ran quick Linpack test using IBT and it passed. Ram is at 4-4-4-17. I could lower the RAM's tRAS value, but I am paranoid about data corruption, so it will stay at 17.
Four_85.JPG


I will leave it as is for now. Even though CPUz shows the VCore at 1.288v, I have it set at 1.300...I guess there is some vdroop even with Load Line Calibration enabled.

Thanks everyone! :)

When I am ready to upgrade next year I will raise the volts to 1.5 see how high I can go and for how long until it dies and post the results here. :D


Edit: I am not sure why RealTemp shows different speed than CPUz.
 
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