Core i7 920
CORSAIR CMPSU-750TX 750W
EVGA 141-BL-E757-TR LGA 1366 Intel X58 ATX X58 SLI LE Intel Motherboard
Coolermaster Cosmos S
G.SKILL 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600
Caviar black TB HD
Everything is hooked up properly, the stock heatsink seems to be pretty snug on the board and it is running. My initial guess to why it is running so hot would be I did not put any thermal compound on it because I wasn't sure the thermal pad that came on the heatsink would suffice. I took the heatsink off last night to check and the pad did melt and spread across the chip as intended, but it isn't getting the job done. Am I right to assume if I put some real compound on it, it would drop the temperature substantially? Or is there something that I am missing, like in a settings or something?
I have an extremely similar i7 920 system as yours, and mine stays around 40C with all fans in my antec 902 running on low. I'm 'just using the stock cpu cooler, no OC so far, and everything is fine.
Judging the fact that you have a cosmos, the cooling inside the case shouldn't be a problem. If your cable management is tidy enough, airflow should be sufficient. Getting idle at 84C is really killing it, if you are not even overclocking it (since you didn't mention I assume you are not)...I don't think it's the problem with the thermal paste. There may be a problem with the heatsink installation, or the cpu is faulty (which is rarely the case). I will suggest you get an budget heatsink like Cogage TRUE Spirit or Scythe Mugen 2 (~$30 for really nice performance) to test your cpu.
If you can have some screenshots of how everything is running, that may give the others a good start in helping you too.