• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

i5-2500k - can't overclock at all, please help

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.


New Member
Apr 19, 2015
Hello everyone,

I have a problem with overclocking my i5-2500k - basically I can't overclock it at all, the computer will try to boot 3 times and then will load default settings.

My specs:

i5-2500K with Noctua DH-15 cooler.
AsRock P67 Pro 3 B3 (BIOS v. 1.90 - I'm afraid to update it because I read something that the latest bios is for Ivy Bridge processors and I have SB (will update to Skylake or something else in the future). So I DON'T have LLC when set to offset mode.
8GB 1333 Kingston (2x 4GB)
GPU: MSI GTX970 Gaming
PSU: Corsair 650TX

I know it is an old CPU and mobo but I don't see the reason to exchange them when they work (at least worked with the OC).

Here are my previous settings that worked fine -
The things that have changed: I bought new case - Phanteks Enthoo Pro and moved everything in there. Added two additional 140mm fans at the top of the case as exhausts. Everything was working fine with the OC. Previously I had Windows 8.1 now Windows 10.

Next I tried to exchange my old audigy 2 for Sound blaster Z (will have to send it back - it just won't fit with my huge *** cooler) and strangely bios loaded default settings. Don't know why and that was it, no more OC for me.

I never could get 4.5 without LLC with nice voltage so I settled for 4.3 which was fine by me.

Now I can't overclock at all - same settings - won't boot. So I set offset from -0.050/-0.045 to 0.005 and up to 0.015. It wouldn't boot. Tried the same with 4.0 instead of 4.3 - no go. So I tried setting fixed voltage from 1.25 to 1.30 at 4.0GHz -nope, nothing. 3x restart and default settings. I am out of ideas.

Home someone will give me some pointers.
Last edited:


Señor Senior, Senior
Oct 11, 2002
The Empire State
Uplug psu from wall, remove cmos battery from board for 2min. Put battery back into board, plug psu back into wall and reboot.

Check out this guide

Also be sure you recheck all your connections since you stated you swapped cases.


New Member
Apr 19, 2015
Thank you! Removing the battery did the trick! Now I can OC and test the system.

What is the max safe voltage for daily use? 1.35 as in the guide you linked ?


I tried 4.5 again at -0.050V and run quick test of prime95 for 1h and 10 passes of Intel Burn Test (Very high level) which passed. My max temperatures on cores: 61C, 69C, 70C, 67C. Voltage was 1.334 (usually), sometimes 1.336 and max was 1.360 few times for like a second.

I know I have to test more but is 1.334 (90% of time) and absolute max 1.360 safe for daily use or should I downclock to 4.3 and try to lower voltage? When I tried to set offset to -0.055v it BSOD on me during IBT. With -0.050v it went ok so I guess that is my lowest possible offset.

I measured with CPU-Z and HWMonitor.
Last edited:


Dec 10, 2003
1.35v is suppose to be ok, then find the most stable overclock, then try lowering your voltage.