Are your room temps the same?
Is the air flow blocked/impeded around the case?
Room temps are the same. The only time I've noticed it return to normal temps via room temp was recently when it was below 0*C outside and I didn't have the heater on. Airflow is as normal. I'd wondered if because the drive is running warmer than usual, that warmer air was being blown into the case, but that would still pose the question 'why is the drive running warmer?' I've ran surface scans on the drive and checked the S.M.A.R.T. readings and everything seems to be fine there.
I'm seriously thinking that maybe the sensors are giving bad readings. While playing a new game the other day, my PC would restart every time I got to a cutscene. The game had ran fine prior to that day, so I decided to do a log of the temp reading on Speedfan to see if overheating was the problem. I don't think it is, though according to the log, my CPU got up to 83*C and the Northbridge peaked at 110*C. I realise the Northbridge on my board gives a messed up reading to start with, but it's never gone that high before. What makes me think it wasn't overheating causing the problem is that I got a log for while I was playing Left 4 Dead 2, and the temps got just as high, yet the computer didn't restart. I'm pretty sure that if those temps were accurate, my CPU at the very least would have fried by now.
As far as I can tell, the GPU is running at normal temps and gets up to 55*C max while gaming. And even if the GPU was putting out more heat than usual, I don't think that would account for why the HDD is running warmer.
I'm completely baffled as to what the hell is going on.