Need help reviving an old system

Hi, everybody. I have a pretty old computer that my grandpa brought in some time ago. When I first tried it out, it didn't POST, but powered on. I tried things such as booting w/o no BIOS battery, booting with a proven good BIOS battery, and other things. It didn't POST, despite all of my attempts. :( Later, I tried again, to no avail. Again, (◕︵◕). I removed the PSU and cleaned it. I installed it back into the system and plugged it in. This time the system didn't even TRY to power on. Today, I wanted to boot the OS on the HDD, and faced the BSOD (different storage controllers) with code 0x7b. I attempted to boot it on my grandma's computer, so that's what's causing the BSOD. I try again in Safe Mode, to get the BSOD again. I reconnected the primary HDD and booted into the computer's factory OS (my grandma's) and the disk is still good. Now back to the computer. I want to get this system back up and running. There are no bad capacitors. What went wrong? Why does the computer suddenly stop turning on after I clean the PSU? How do I bring this computer back to life? Please help me and thanks in advance!
 
Solution
You will never get the hard drive to boot on other hardware . Not possible . Unless you format it and reinstall a fresh copy of windows on it .

Tell us what this computer is . What hardware and what operating system or its impossible to help you
It is a custom built computer that at the time I pulled the HDD, the computer had Windows XP Pro.
**start of parts list**
Floppy Drive: Some no-name drive with a sticker on it that has a barcode on a sticker that has this on it:
D359T6 157200 7F16FCO221
I have no clue what that is.
PSU: Enlight Corporation of unknown wattage (wattage not listed) /w date code 0041 (made in 2000?)
S/N: 00102412
HDD: WD800 80GB HDD
MoBo: PLE01 made by an unknown company (Asus I guess?)
CPU: VIA C3 processor
Ethernet Card: COMPAQ 10/100 PCI ACTTON UTP Controller
SP#: 123494-001
DG#: 122849
AS#: 122849-001
CT: P222B01AFJFMIV
REV: A
Modem: U.S. Robotics modem
S/N: 4MBHX23H2096
Product: USR5699B
CD-ROM 1: HP MTCR-4804TE CD-ROM drive
Speeds: 4x/4x/24x
HP S/N: PH045C7D21
P/N: Not Listed
H/W Version: 03
F/W (firmware) Version: 2.6C
Manufactured: October 2000
CD-ROM 2: HP LVLDB-0201 CD-ROM drive
Speeds: Not Listed
HP P/N: Q2108-56000
S/N: MY3588271N
H/W Rev. (revision): D
F/W Version: 1.25
Manufactured: May 2003
**end of parts list**
 
I would replace the power supply . A corsair CX 430 would probably have plenty of juice . But check the connectors are compatible

Unlikely you even have a 4 or 8 pin socket on the mb , but you would almost certainly need to check the number of pins on the board main power connector . Its likely to be 20 pin , and not the 24 pin you see today
But then most 24 pin power connectors have a 20 pin section and an additional 4 pin section that you can unclip
 
Thanks. The motherboard has no CPU power pin (low wattage, I guess?), a PSU that has some unusual dimensions (do you want a photo?), and a motherboard that has a 20-pin connector. Also, the PSU is 14 years old, not 15. The last 2 numbers are 41. That indicates the week that the item was made, so the 41'st week of 2000. We are nowhere close to the 41'st week of 2015, but I can see where you got the 15 year old estimate.
 
PSU photos(just in case) :

86574.jpg


04650.jpg