Computer Overheat? Computer Power Down

[Kruxxor]

Hello,
I has a few questions as i am encountering problems with running FFXIV,
So I am looking for some input, a little help, a bit of insight to narrow down the problem that has plagued me for a while now,
To the point:, I can run FFXIV fine for long periods of time, But on some occasions my computer will just power off without reason, and when this happens it will repeatedly happen for some time with in 20 minutes of it first doing so. It sucks..

My Rig:
OS: Windows 7, 64
mobo: Asrock N68C-S UCC GeForce 7025 Socket AM2+ VGA
CPU: AMD Phenom II x4 955 BE 3.2
Ram: 2x2GB DDR3 1333mhz/PC3-10600 Memory
GPU: Asus HD 5450 Series 1GB GDDR3 PCI-E

I believe my system is overheating but i am not very sure of the temps my GPU or CPU should be about at idle or full load, I've monitored them at:

CPU Idle: 50c~ Upwards
GPU Idle: 58c~ Upwards

While running FFXIV i see them rise to

CPU @ 66c and GPU @ 79c

Is my GPU overheating and would that cause my system to shut off? Is the CPU temp fine or is this too high?

My CPU has recently started making a lot of noise running FFXIV - So I bought some compressed air, blew the dust out of my case and off of my GFX card, now it's silent.