Powercolor 4870

Ok I'll try to make this as simple as possible. Some time ago, I removed my 500 watt PSU from my main computer, which at the time was powering everything, including a Powercolor HD 4870. I replaced it with an 850 watt PSU, and then, later on, upgraded from the 4870 to a 6970.
Now, I have decided to install the 500 watt PSU and the 4870 into a secondary computer I have here.
The 500 watt PSU WAS CONNNECTED AND WORKING with the 4870 in computer A, but now that I have put it into computer B, there is only 1 6-pin power connector, and there are two 6-pin receivers on the card. All googled references state that the 4870 must have TWO 6pin power connectors, yet the very same PSU that was running that card only has ONE 6 pin connection-it is even stamped "PCI-E" . I can't remember if there actually were two 6 pin connectors when I removed the PSU, or when I removed the GPU.
Do I have brain damage or am I missing something obvious ?
I know I can go get a molex>6pin power adapter for a few bucks, but being that there isnt even 2 6 pin power connections on the PSU, how the hell was it working in computer A ?
What would happen if I turned on the computer with only 1 6pin connector connected to the card ?
I don't want to damage the computer or the card, but I do wish to continue working on it without first having to drive all the way out to Fry's for an adapter.
I hope this post makes sense, because I might just be going loony here .
:-D

 

Well, thats ok. I'll be able to go to Fry's today and get the adapter . Still curious what would happen if I turned on the system, though . . ..

 

You wouldn't hurt anything. I ran a video card that required 2 power connectors for a time on one power connector. As long as I stuck to basic tasks the card ran fine. If I tried to do anything strenuous, like run a game, the card would generate a blue screen. Of course, that went away once I got both power connectors hooked up.

 

ok well dang. I didn't get around to going to Fry's yet, but its on the agenda for later today .