VRel issue. Can't rise the voltage

[Vencam]

I started overclocking my GTX 770 OC 3gb, using MSI Afterburn, GPU-Z and Heaven. I Raised the clock to +110 with no problems, when i reached +120, i had some glitches running Heaven, totally normal. But when i raised the voltage (+10 mV) GPU-Z showed a votage rise in the beginning, then it went back to the previous value, and in the PerfCap Reason slot i had "VRel". What did i do wrong, why isn't the voltage rising?

 

[i7Baby]

What did i do wrong, why isn't the voltage rising? - it won't rise if the gtx gets too hot.

 

[Vencam]

Not ever reached 70 celsius.

 

[i7Baby]

But it could go over that under load.

 

[Vencam]

It didn't, Afterburner showed a top temperature of 68 during all the benchmarks i made.