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OC 2600K needs "Internal PLL Overvoltage" enabled past 44x and a lot of vcore, why?

post #1 of 5
Thread Starter 
Hi guys!

First: sorry if I do spell mistakes, I'm from Switzerland and speaking German most of the time tongue.gif And sorry for the long post... But I'd like to give as much as details possible.

My rig:
- Intel Core i7 2600K (D2 stepping)
- Noctua NH-U12P (1 fan @ ~50-80%)
- ASUS P8Z68-V Pro @ BIOS 3603
- 2x4GB Corsair DDR3-1600, CL9, 1.5V
- Seasonic X-660 PSU, Lian Li Case (1 fan)
- GTX 570 Phantom (OC @ 800MHz)
- Win 8.1 Pro 64bit

I bought it 2 years ago and was running it @ 4.0GHz all the time. I never messed with vcore and stuff, just put ratio 40x and left all @ default, but it was rock stable (checked with Prime) and never had stability problems.

So yesterday i thought of truly overclock my 2600K. I read the whole day in forums and how to do it on Sandy Bridge, because last time I did this was 5 years ago on my C2D E8400. My goal is to reach 4.8 GHz as a 24/7 OC. But since most of the time it will be idling @ 1.6 GHz (using as a Media Center), it shouldn't hurt too much.

After trying hours to get 48x ratio stable, I gave up for now and I'm prime-testing 44x ratio @ 1.328V (it was unstable @ 1.312V). My max. temp right now has reached 85° (on custom blend 90% ram), pretty high I think, but I'll see how it goes... I still can put the fan to 100%, maybe install a second fan on the cooler and reseat it with new better cooling paste and also remove some dust.

My BIOS settings:
- BLCK: 100.0
- Memory: 1600-1.5V-CL9
- LLC: medium
- VRM: Fixed 350
- Phase: Optimized
- Duty: T.Probe
- CPU Current: 100%
- CPU Voltage: Offset Mode
- Offset Voltage: +0.010 (right now)
- All Voltages @ Auto
- CPU Spread: Auto
- EIST and VT-d: enabled (for idling at low vcore and VMware)
- C1E, C3, C6: disabled (I need that because of BF4 micro stutters)

This are my problems @ 48x:
- I need Internal PLL Overvoltage enabled for a 45+ ratio, or it won't boot to Windows. Why is this? Is there a way to keep it disabled and tweak other values? Because with it enabled, it takes longer to POST (sometimes also double POST), and Standby (S3) doesn't work anymore...
- I need a hell of vcore @ 48x ratio. I wasn't able to boot with less than 1.440V and I think it needs 1.464V or more to be stable... But then my cooling can't keep up with so much heat @ prime... Is there something I can do/tweak to lower my vcore?
- I tried with Phase and Duty @ Extreme, with CPU Current @ 140% (still don't know what this really is for), different LLC settings, VRM on Auto, but it doesn't seem to make a difference... But I still didn't play with the other voltages settings.

Did I miss something? Some setting/tweak/trick? What could I try out? I hope you could help me out with this. Thank you very much!
Edited by pvalerio - 11/4/13 at 2:02am
post #2 of 5
Might be just bad luck on silicon lottery.

My i5-2500k does 4.8 at 1.39v. Two years ago it was at 1.37v. Had to up the voltage a bit every 8-10 months.

If it doesnt boot with 1.440V that sounds like you need a hefty amount of vcore...

Try upgrading your cooling, or up the fan. Your CPU is probably just too hot to handle with the cooler you have at the fan speed youre operating at. You lose a lot of static pressure especially if you lower the fans to around 50% power, thats why i have my fans in push/pull so i can run them at such a low RPM.
Edited by Aesthethc - 11/4/13 at 2:06am
post #3 of 5
Thread Starter 
Yep, sound like I haven't got a good 2600K for ocing...

When I get home I will clean and reseat the cooler, put the fan to 100% and maybe add a second one. I hope I can lower my temp a bit... Then I'll try to get a rock stable 4.4 GHz OC and maybe try again for 48x ratio.

I'll let you know! And thanks!
post #4 of 5
Yeah on my old 2600K i needed PLL over voltage for anything past 45 multiplier. Sounds normal to me.
post #5 of 5
Thread Starter 
Ok, that sucks but yeah nothing we can do about it.

I just came home and to my surprise my computer is still running prime without errors (9h so far). Also temps seem ok. I'm gonna tweak now all the voltages and other settings. Then I'll give it again a shot for 4.8 GHz, but I think I'll just stick with my 4.4 GHZ OC.
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