I'm running 2 Cards, on Windows 7 Ultimate 64bit and have a Silverstone Strider 1500w PSU
Do you use stock coolers? In auto mode or on 100% rpm?
I can't get, how do you keep temp at 68C.
My cards are separated with pci-e risers and heat up to 75-80C.
What software do you use for OC, MSI AfteBurner?
My 5850s are the sapphire xtreme ones, stock coolers running at 65-70% fan depending on the days temp, running at 100% will kill its life time
I'm using sapphire trixx for the OC, not sure why you are getting such high temps, maybe your OC software is automatically bumping the voltage.
I found that my 5850 Xtremes with stock coolers and stock voltage would run at around 72*C and 78*C even with the fans at 100% (not recommended). At the time the ambient temperature was about 20*C. Ventilation wasn't the best but it was ok. I'd imagine a single card would be at around 70*C but haven't verified this.
Perhaps noogai93 has good ventilation, low ambient temperatures, or is using case fans or something to blow cool air between the cards. If you're struggling to obtain low enough temperatures then I'd consider undervolting the cards.