Need help with this World War 1 machine

Cybran

Reputable
Jun 28, 2015
15
0
4,510
I'm assembling for no reason at all this magnificent dinosaur and I need help.
I had a motherboard in the case already which I replaced with this one along with the CPU. All good, everything runs smoothly. The CPU, RAM, etc, onboard graphics communicate too, nothing is off, didn't reinstall Windows though, because the HDD seemed to not need that. It adapted perfectly, got the rest of the drivers off the net. But when I connect the AGP and turn it on, the HDD led stays lit and I can hear the GPU's whining. I've connected the 6 pin power connector through a molex adaptor. Could that be it? I'm a enormous noob. I don't know what could be the problem. I need a professional troubleshooter.
The model of the AGP is Gainward 7800GS 512MB.