Install without backplate is fine, but you need to be careful...over tighten the board will bend. I have tried Xigmatek backplate, even though it says M4 screw, it's not compatible with Alphacool's M4 screw. It must have been a mistaken labeling on Xigmatek part. I've just placed an order for Watercool Heatkiller 1366 backplate (stated M4 screw), and I hope it is compatible with Alphacool mounting screws. Crossing fingers.

Alphacool CPU blocks are nice, but the instruction is mediocre at best. For example, I have the optional CoolCover and the instruction said to tighten knob until...hmmm...to look like Bundy's illustration photo a few posts back. However, for doing so as per instruction, the board will bend like a solar eclipse (crescent). The problem is the spring is too long and the cover tube is too short. Oh well...I hope the Heatkiller's backplate solve this issue.