can i put this ram into my imac 21.5 mid 2010 corsair cmso8gx3m2a1333c
A quick Google suggests that memory is two 4 GB SO-DIMM sticks of 1333 MHz DDR3, which matches the specs given by Apple and EveryMac.

It's possible that you've just got a couple bad sticks of RAM. I'd suggest testing them one at a time, rotating through the slots. If possible, test in another machine as well.