Hello, I recently upgraded to a 5770 (It was at a much better $209, compared to the very steep $600+ for the 5870), and want to put my old Gigabyte HD3870 in my brother's machine.
When i put the card in and hook everything up and press the power button, nothing happens, however, if the card is removed (it still won't power up even if the card's power is unplugged), the computer fires up normally.
He has a 400w power supply, and despite the manual saying that is what the card needs, i still think it's a power related issue.
What I'm wondering is if, say, a 450w or 500w would be sufficient to get it going.
The reason for the gradual rise of power above is due to budget restraints, as my brother can't afford the $200 620w i have, and in all honesty, I don't think he really needs that much anyways.
Well there's the problem, so let's see what everyone thinks.
That could definitely be a PSU issue (sounds like it is quite likely from the circumstances). A 3870 will run fine on a good quality 450 or 500W PSU easily. It will even run fine on a good quality 400W. Look for a Corsair or Antec or Seasonic or similar PSU in the 400-500W range and you should be set. It might be worth trying his PC with your PSU though just to make sure it boots with a different PSU- verifies that is what he actually needs;-)
That is probably the case, what I suggest doing though is (just to verify before you spend a bunch of money) take the PSU out of your computer and plug it into your brothers- this will verify that it truly is the PSU and not some other compatibility issue.