I actually acquired a PC Gfx card a while back that had a special slim-line custom fan with sense line bolted onto a heat sink. Unfortunately, the reason I ended up with the card was down to the fact that one of the vanes was missing from the fan.
Not knowing whether a lack of a RPM sense input to the Gfx card would cause the card to automatically shut down, I ended up bolting a AMD processor cooler fan to the heat sink as these fans have the same three lines as the original fan (Yellow was the sense line...Just to confirm that), even though the relatively low end Gfx card now takes up two bays rather than the one just due to the fan!
Yeah, if you can buy a fan adaptor for next to nothing, then go for it. It is possible to splice into PSU rails, but in order to a really decent job (E.g. Not actually cutting through the wires at any point in order to keep resistance as low as possible, using heat shrink by disassembling the Molex plug at the other end to get the heat shrink on, etc) it can take some time.
Anyway, enough of my ramblings ... Hodgkinson.
