PSU pins getting bent...lined up triangles, latches, and still bent?

Twice now I have inserted my PSU into the motherboard and when I hooked up the hard drive and monitor, nothing was displayed on the monitor. My optical drive was blinking green, but would not open or close. When I removed the PSU from the heatsink and motherboard, I noticed some pins were bent. I lined up the triangles, and the latch fastened w/o any problems. What secret or advise can you give me to properly apply the CPU to the motherboard? What am I doing wrong? Also, could it be the motherboard (or something else) is bad? I have two sticks of RAM, and I have put them paired up in all four DIMM slots. When I turned on the computer with and without the heatsink, the optical drive both times had a flashing green light.