HDD Power down randomly

My harddrive(s) have been powering down recently at random times. What happens is my computer will be on for a bit, doesn't really matter how long (so I don't think its heat buildup in my machine, and besides I have 5 case fans), and my hard drive (not sure which one, but I think any one of the three) will make a noise like its shuting down to save power. Sometimes it will come back on, but usually it hangs my system and then I have to restart my comp. I have narrowed it down to a few possible reasons why I'm having this problem.
1, which I think I can rule out, is its a heat issue.
2, the PSU is using up too much power between everything else, but I doubt that, as I have done my math and I think I have enough wattage comming from my PSU.
3, the SATA cables come loose intermittenly and need to be put back in place
4, the SATA controller (native to the MOBO) is crapping out.

Now I honestly don't know how hot it gets in my case, but I think the 5 fans I have (3 blowing in, 2 out) should be enough to keep it cool.
The PSU is 420W, and I have on my mobo:
A8V deluxe MOBO
3500+ 64bit AMD proc
2x512 DDR400 RAM
x800 AGP Radeon Video card
Audigy ZX 2
Wireless NIC card
Haupaugge 150 PVR
Lite-On DVD/CD RW
Lite-On CD-ROM
120GB Western Digital HDD SATA
200GB Western Digital HDD SATA
13GB Maxtor HDD PATA

I have noticed that when I powerdown my comp, I can't simply restart it because it doesn't read the SATA HDD, but if I open my case and just move the cables a lil bit, it works again. I really think my problem is being caused by the cables comming loose but I've never had that problem untill I added my 3rd (the 200GB) HDD. Has anyone else seen this problem, and/or could give me some advice how to fix it? its really annoying to have to open my case up to fix the HDDs everytime.

 

lil bump