CPU speed rules all. Every little bit helps. Also, you realize that stock voltage on those ballistix is 2.2v and not 1.8v. It may be stable, but I would definitely run a memtest for 3 or more passes at that voltage to be sure.
You can go a bit more on the load temps. I would say 60C or less is fine.
I also agree that 3dmark is bunk. I went from 13184 to 16160 going from an E2140 @ 3.5 to a Q6600 @ 3.6. That is an amazing jump for a CPU alone. I know the Q is a bit better due to cache, but I don't tyhink i was bottlenecking my GFX card that much with the E2140.
I say try the 174.70 (or was it 170.70, lol) and see if you have any change. Also, try it with the CPU clocked up some more and see if it starts to go up.
So you think I should run 3GHz or more and try it?