The first card I ever modified and did serious work on was an old Voodoo 5.
I took off the stock heatsinks and fans, cleaned the card up, put a lot of time and effort into modifying coolers so that they would fit the twin GPUs (Voodoo 5's had two GPUs on them), fitted out copper RAMsinks, and attached everything very carefully. This was the first card I had ever modified, and I was terrified that I'd scratched some micro-trace, shorted something with Arctic Silver, or made some other deadly mistake and killed my souped-up pride and joy. Once I was done fitting the card out and whatnot, I installed it in my computer and fired everything up.
I got no post screen, and crazy error bleepings from the motherboard.
I went insane with frustration and rage - the product of all my work, time, and money was destroyed, leaving me with nothing! I tried all kinds of stuff, but the card wouldn't work.
So I got really inebriated, and went to bed, sad and tired.
In the morning I got up, looked more closely, plugged in the card's power cable (I had missed it the night before, with the coolers on there it used three molexes, and a video-card using a molex plug was a rare thing back then), and started enjoying my hard work
.
The moral of the story is that you should always check power cables
.
There're pictures of the card in
THIS thread if anyone cares
.