Hit a 4Ghz wall @1.35v core shutdown, ideas?

[OC Nub]

I agree with famish99, your temps are to high and may cause instability. Your ram is rated at 1.65v, try 1.640v, I have the 2000GT's also, I think 1.53v is to low. Also your IOH is high, I have a gigabyte board but if that is the same as IOH core try 1.140-1.160v and link that with your QPI PLL so both are running at the same voltage. Try 1.40v-CPU PLL, that may help lower temps.