My specs are:ASUS P8Z68-V PROIntel® Core™ i5 -2500KMushkin Enhanced Redline 8GB (2x4GB) 1600 7-8-7-24 model 996999EVGA 015-P3-1580-AR GeForce GTX 580Corsair CMPSU-750AX Professional Series Gold AX750Corsair Hydro Series H100 extreme performance liquid CPU coolerWindows 7 Home Premium SP1 64-bit OEM (PC) 110I have the cpu auto oc'd to 4.2 using the AI OC Tuner X.M.P. feature. However when I change it to Manual and then click OC Tuner + Yes, I get an immediate black screen and re-boot. Does that mean 4.2 is the best this cpu can do?? Thanks for any feedback--- and Happy New Year!.Bruce

Might need to up your VCore a bit.

My specs are:ASUS P8Z68-V PROIntel® Core™ i5 -2500KMushkin Enhanced Redline 8GB (2x4GB) 1600 7-8-7-24 model 996999EVGA 015-P3-1580-AR GeForce GTX 580Corsair CMPSU-750AX Professional Series Gold AX750Corsair Hydro Series H100 extreme performance liquid CPU coolerWindows 7 Home Premium SP1 64-bit OEM (PC) 110I have the cpu auto oc'd to 4.2 using the AI OC Tuner X.M.P. feature. However when I change it to Manual and then click OC Tuner + Yes, I get an immediate black screen and re-boot. Does that mean 4.2 is the best this cpu can do?? Thanks for any feedback--- and Happy New Year!.Bruce

You need to have "Internal PLL Overvoltage" set to enabled. Also, try loosening up the timings on your RAM a bit. Maybe 9-9-9-24?Don't be afraid to push the voltage up, you have an H100. If you want to go to somewhere around maybe 4.8GHZ, give it maybe 1.4 volts. It's totally fine with an H100.ALSO, be sure to scroll all the way down and disable "CPU Spread Spectrum".

Jim -Thanks! I thought that might be the case, but I don't know how to do it. I thought you had to do that in the OC Tuner.???Bruce

Jim -Thanks! I thought that might be the case, but I don't know how to do it. I thought you had to do that in the OC Tuner.???Bruce

Scroll down a bit and set the CPU voltage to "Manual". Then set the voltage to 1.4 and set the multiplier to 48.

Okay, I'll try again.

Stop using OC Tuner. That tool is useless. I have the same BIOS.You have to overclock using manual settings and manual Vcore. Plus PLL Overvolt to on, but only if it fails without.Set XMP, go to CPU settings, turn off turbo and set your desired multi. Keep C1E on, other management thingies off.I wouldn't recommend doing what benorg recommended, going straight 1.4 and 48x multi. It can be OK, but it mustn't. I always preferred step by step, especially seeing how much Vcore step was needed, thus deciding when to stop, otherwise you neverk now where you wall is going to be.I'd just step up to 44x, see how it holds.Be sure to test between each upping of the clock. If unstable in torture test, up the Vcore. Keep checking temperatures.

Stop using OC Tuner. That tool is useless. I have the same BIOS.You have to overclock using manual settings and manual Vcore. Plus PLL Overvolt to on, but only if it fails without.Set XMP, go to CPU settings, turn off turbo and set your desired multi. Keep C1E on, other management thingies off.I wouldn't recommend doing what benorg recommended, going straight 1.4 and 48x multi. It can be OK, but it mustn't. I always preferred step by step, especially seeing how much Vcore step was needed, thus deciding when to stop, otherwise you neverk now where you wall is going to be.I'd just step up to 44x, see how it holds.Be sure to test between each upping of the clock. If unstable in torture test, up the Vcore. Keep checking temperatures.

He can see if 1.4 volts @ 4.8GHZ is stable, THEN, slowly bring down the voltage. With an H100, temps are totally safe @ 1.4volts.I don't understand why people are so afraid of voltage when they have a very nice high quality CPU liquid cooler.

Before I saw Word Not Allowed's reply I found the voltage settings and changed to 1.4v and set multiplier to 48. Just got another black screen and re-boot going to OC Tuner. Will go back and try Word Not Allowed's recommendations now.

Stop using OC Tuner. That tool is useless. I have the same BIOS.You have to overclock using manual settings and manual Vcore. Plus PLL Overvolt to on, but only if it fails without.Set XMP, go to CPU settings, turn off turbo and set your desired multi. Keep C1E on, other management thingies off.I wouldn't recommend doing what benorg recommended, going straight 1.4 and 48x multi. It can be OK, but it mustn't. I always preferred step by step, especially seeing how much Vcore step was needed, thus deciding when to stop, otherwise you neverk now where you wall is going to be.I'd just step up to 44x, see how it holds.Be sure to test between each upping of the clock. If unstable in torture test, up the Vcore. Keep checking temperatures.

And why exactly is that bad? I went straight to 1.488 and even went higher to 1.5 for testing purposes....I've had this new computer for a month now and nothing's wrong with it. I see no reason why you shouldn't go that high since the limit is 1.52.

I don't know where C1E is or which turbo(I saw Turbo Ratio and Turbo Mode) setting to turn off. Right now I'm lost. What I really need is a line by line step by step process outline. I'll keep trying though. Thanks all.

Even with temps in check excessive voltage can brick your chips. Eletromigration can happen with too much Vcore.1.4V may be ok, but I prefer to keep it under 1.375V since that's the maximum recomended by Intel for their 32nm CPU's

Even with temps in check excessive voltage can brick your chips. Eletromigration can happen with too much Vcore.1.4V may be ok, but I prefer to keep it under 1.375V since that's the maximum recomended by Intel for their 32nm CPU's

Intel says the MAX voltage for Sandybridge is 1.52 volts.Why in the world would a multi-billion dollar company throw out that number for no reason? Those engineers have tested the chips plenty more than us on the forums. I really feel that as long as you are below the 1.5V mark, and your temps are fine, there is nothing wrong with putting voltage that high.I will take some of your advice and push the voltage lower, but going around telling people with H100's to not go above 1.375 volts is just nonsense.

The level of advices on this forum is currently subpar.Right now avsim is down, so I won't type much (iPhone is working OK), but I recommend you refrain from going 1.52 just because someone said it's safe according to Intel. And no, Intel did not say it' safe. If you brick it, you lose guarantee.If Benorg and co like risking, they should say so (didn't).

The level of advices on this forum is currently subpar.Right now avsim is down, so I won't type much (iPhone is working OK), but I recommend you refrain from going 1.52 just because someone said it's safe according to Intel. And no, Intel did not say it' safe. If you brick it, you lose guarantee.If Benorg and co like risking, they should say so (didn't).

Well.... now running stable @ 1.39Vcore @ 4.8GHZ. I'll see if I can srop it even lower. :)