Before reading any further. Did you check inside of this PC, is it IDE or SATA setup? If SATA (IDE as the same but leave DVD and floppy connected
0 - disconnect everything inside except HDD and RAM, disconnect any cards you see inside, even your DVD drive, leave only monitor, mouse and keyboard and try to boot, if nothing - proceed to this reading.
"I've only seen input/output errors one time and I was getting BSOD everytime I try to bootup, I also blamed the hard drive and reformatted to reinstall windows. But then windows installation cd wouldn't install, I also had a backup image and that wouldn't install, I tried a new hard drive and that didn't work either . The problem was a bad motherboard.
You can try using a linux livecd and see if that can bootup the computer. That can at least test some of the hardware."
I would not buy anything new for this PC. You need to actually boot to any Operative System to make sure that your basic hardware is working. If your motherboard is dead or almost dead, then what. Bad RAM would not give you only BSOD, you may not boot at all with screen staying black, or you could have problem with WIndows.
Also, consider this - you have no idea which OS was installed.... Do you have any spare OS?
If no, I would try to boot using linux livecd, or linux distro - you need to make sure that something works inside, well you need motherboard to show signs of life, or you just wasting your time.
After this, if nothing works, take a deep breath, step back, take a screwdriver and take apart this PC - this is junk - your time is more important than deal with so many unknowns.
That is a good point! I ran Memtest from a Linux distro. After determining RAM was bad I got scared and replaced the old PSU with a Corsair CX430. Luckily I was able to get some replacement RAM sticks from Geil under warranty. Then I got a new WD blue 1tb for $50. The only mistake that I can find now is the over zealous purchase of windows 8.1 32 bit. Which led me too my next thread (http://www.tomshardware.com/answers/id-1901641/windows-...)