there is nothing wrong here temps are fine
1. unless you have vsync enabled cggo will up upwards of 120fps
2. its a 5850 they run a fair bit warmer at idle then more recent cards
3. csgo has stability issues on somecards .. its got a memory leak try rolling back to older drivers
1. CSGO is a CPU bound game
2. I agree, but 5850's are not that hot, not in the slightest
3. The memory leak only happens if you tab out and minimise the game.
OP should check for dust, repast the card, and also ensure that he has a decent fan profile set. CSGO is not the problem here...
It's also worth mentioning that the OP hasn't mentioned his PSU besides 650W. For all we know his PSU can't handle the load. It could be a highly overrated PSU from crap-brand-mcghee.