ASRock or Gigabyte P55?

I would go Gigabyte over ASRock. MSI is coming out with a motherboard that has a new chip in the end of October. This chip will allow many different multiple GPU options. The board is called the Big Bang, unfortunately I doubt it will come close to this price range.

Gigabyte has certainly earned a recent reputation for producing quality motherboards. However, ASRock has stepped up their game in the past year providing top notch mobos for both the Skt775 and Skt1366 platforms. I am currently using 3 ASRock mobos (HTPC, NAS, and mykids computer) without any issues or problems and can easily recommend ASRock as a stable and value added foundation for any machine.

Given that the Gigabyte and ASRock you linked are for the same price, I would suggest making your purchasing decision based on features and independent website reviews. Not to discount the user reviews on Newegg, but they can sometimes be suspect. Personally I prefer an ATX sized mobo over a micro-ATX unless I have specific reason to use a micro-ATX.

Regardless, I believe that either mobo will perform to your expectations.

I prefer Gigabyte.

But if it comes down to two comparable motherboards at a similar price, the next discriminator should be board layout. Will a full size GPU cover the SATA ports? Will an installed PCI card block the air going to the GPU? Will any motherboard components around the CPU limit heatsink choices?

Things like that.