XFX Radeon HD4670, no signal on monitor when used.

I agree that it's the psu. Wait for some more answers...

So the new psu didn't work. But my friend told me that he tried the vga slot on the card like I am and it didn't work for him either, then he had to use a vga to dvi converter so it worked in the other slot. And then it began to work. Also he said that vga worked only when he used dual monitors, so I don't know what's going on. I'm really scared about not knowing what the problem is, I'm going to try the adapter thing tomorrow.

InfernoRogue said:

So the new psu didn't work. But my friend told me that he tried the vga slot on the card like I am and it didn't work for him either, then he had to use a vga to dvi converter so it worked in the other slot. And then it began to work. Also he said that vga worked only when he used dual monitors, so I don't know what's going on. I'm really scared about not knowing what the problem is, I'm going to try the adapter thing tomorrow.

Well why didn't your "friend" tell you that in the first place

I have no idea. But the adapter didn't work either. I used a vga female to dvi-i male adapter, didn't work. I'm really scared guys, I have no idea what the problem is.

Not sure if I mentioned this already, but the usb ports don't work either when I have the graphics card in the mobo. It seems like none of the cables connected to the motherboard from the computer case function when the graphics card is in, like the led lights and such.

After replacing the PSU with a 750W one, after trying out some adapters, the combination still doesn't work.
That leaves only one thing: The GPU doesn't work!
We all (including you) believed that the MoBo and gpu worked in your friends pc but with a more powerful PSU.
You replaced the PSU, and the problem isn't solved.

At this point, I would take out the card your friend gave you, and go back to him/her and test it in his/hers PC to see if it even works

Does everything work if you remove the card and use the on-board graphics? I know you said this earlier, but is it still the case?

One thing that is often overlooked is motherboard alignment in the chassis. Remove the graphics card, slacken all the mounting screws (don't remove them, just undo them enough so that the board is free to move slightly) and then replace the card. See if that makes any difference.

While doing what Dwarf said, you must be grounded. While unscrewing the motherboard, your forearm (Roll up your sleeves if you have them) must be touching the edge of the case in order to discharge the static electricity that piles up on our skin and clothes. You must be careful not to damage any "little barrels" (capacitors) with the screwdriver you will be using.
Of course, you must unplug ALL cables, and before pulling out the power supply cable, turn of the little switch to O. Put the PC on a flat area and begin.