I have used the P55-UD3R motherboard. Did you have specific questions?
I've built 2 with the i5-750 and UD3R motherboard, using a couple of different Xigmatek coolers. I used 8GB of Ram and Win7-64 bit. Both machines were able to exceed 3.9GHz without any careful tweeking of settings, and with reasonable temperatures. We use them everyday in our office and run them at 3.5GHz for that.