I5-2500 stuck at 3.1Ghz

[grazed]

Hi, my (non k series) i5-2500 seems to be stuck at a x31 multiplier under stress such as Prime95. Sometimes for a brief moment it will clock at 3.3Ghz when I start the test, however a moment later it will shoot back down to 3.1Ghz. Both CPU-Z and CoreTemp are reporting the same multipliers.

I'm using a Biostar H61 board, single / dual threaded turbo works (3.6Ghz on 1 Prime95 thread) and this is what I've already tried:

- flashed BIOS
- disabled speedstep
- disabled turbo
- forced x33 multiplier in BIOS
- disabled C1E
- increased TDP to 300w (the locked 2500 never goes above 60w~, but just to be sure)
- disabled BIOS power saving
- disabled Window's power saving settings

Thermals never go above 55c during Prime. Any ideas would be much appreciated.

 

[grazed]

Just tried increasing vcore with no dice. Could it just be a defective board? Makes no sense since everything else is perfectly stable.

 

[amuffin]

So, what's the problem?

4 Cores will run at 3.1ghz.