It's 3 ghz but he can overclock it to 3.4 or something around that.
So will an HD 5750 or 70 bottleneck with 3.4 ghz ?
At any clock speed that Pentium D would bottleneck. Just stick a 6570 in there.
I have an older hackintosh with a Pentium 4 540J with HT @ 3.6GHz paired with a GeForce 7900 GS OCed and the P4 still bottlenecks it in most cases. I know we're talking about a Pentium D but that's not worlds a part from my Pentium 4 HT.