I got a 4870 (was working fine a month ago, in a different pc), i´m testing in a old pc but it doesnt work..
-Asus P5GD1-VM (775)
-P4 3.0 Prescott
-PSU 400W (the guy i bought the card have the same PSU, and it was working fine)
The motherboard recognizes something in the PCI Express slot (it has onboard vga), because the onboard vga turn off..but i cant get image in the 4870..and the pc looks like it jam. The fan is working, the card gets warm.
I made a huge mistake when i plugged the 6pin conector to the psu, i plugged it backwards (white connectors)..after 2 minutes testing, i saw the mistake and fix it. Did this damaged the card?
Other thought, last summer a shot circuit in the card, damaged a 8500gt..since then i didint try any other pci-express card. Did this accident damaged the pci-express slot? The symptons are the same, card gets warm, mobo recognize the card..but no picture.
-If i connect the graphic card without the molex..will it work? Before i messed up with the molex, i started the computer without any molex plugged in. The symptons were the same (fan was spinning, card was warm, no signal on LCD), but at the time i thought the PCI E was not delivering enough power, so the card wont boot.
- Then i plugged molex in the wrong way..tried for 2 minutes, no signal...when i saw that the molex was not correctly plugged, i turned the pc off and fix it...same symptons.
It´s hard to believe that two minutes with the molex plugged in the wrong way damaged the card, insted using 12V i used 5V!!
If you don't plug in the power you can also fry the card. I did it with an old ATI 9800 Pro. I think the first second with the power plugged in wrong damaged the card. This is not like a bridge where you can drive on it for years till something cracks, think of it as putting your car in reverse while doing 90. Not going to take long to break something. However, if your PCIe slot is damaged, it could also damage the card. So once you try it in your PC, then move to another, the card is damaged. To be safe I'd get a new Motherboard unless you want to risk killing another card.
I believe more the PCI-E is damaged or bad grounding in the PC or bad PSU..
I´ve searched a lot about people using Graphic Cards without the molex plugged in..most of them say that the card works ok until the play heavy games or the computer wont boot. But if u say that happen to u..i believe
About the molex plugged wrongly, i doubt that it damaged the card..i didint overvoltage the card. It´s like using a old PSU +12V 13A in a new PC, the computer wont start due the lack of power (I think). In HDD, pluggin the molex wrongly can damage the hard drive, because it´s injecting 12V into 5V.
It didint smell fried and none of computers gave Bios Beeps.
The card is fried or damaged, X*X will give the vereditc and i´ll post the result of RMA. But not very optimistic
Until then, no more graphic cards in this pc!! eheh