Strange tick tick tick noise

So I installed a new PSU (Earthwatts 500) maybe 2 weeks ago, and a Radeon 6870 last weekend. I also have a continuous train of dead pixels that started after I installed my PSU, but before I installed my GPU (not gonna ask about that here, but just incase it's important to this other problem - for reference, my thread on it is here http://www.tomshardware.com/forum/330972-28-mess-monito...).

I noticed some of the time I hear this strange clicking noise coming from my PC, it's been happening for the past 5 days or so. When it happens, it occurs at a very consistent speed (it isn't happening right now so I can't count, but I guess around 1 tick per second). Given the fact that this is the second concern I've had since installing new hardware this month, I'm rather concerned there's some underlying issue.

HP Pavilion p6230y
OS - Windows 7 Home Premium 64-bit
CPU - AMD Phenom II X4 810
RAM - 8 GB DDR3 @ 533MHz (7-7-7-20)
Motherboard - Foxconn Aloe, chipset vendor and model is AMD 785GSB700
Graphics - ATI Radeon HD 4200
Hard drive - 733GB Seagate ST3750528AS SCSI Disk Device (RAID)
PSU - Antec EarthWatts 500W
Monitor - Acer X203H

I'm also not sure if this is a related issue, but my computer started overheating like a mother this afternoon, I was playing Starcraft 2 and it hit 70 celcius (I think my normal is 45-50). I turned SC2 off and was still hovering in the 60s for awhile.