I recently tried adding ATI 5770 graphics card to my PC (using PCIe x16 slot, with a 6 pin PCIe power cable adapted from a 4-pin molex), and it wouldn't boot up with the card in there. The power supply in the PC is a very basic 350 Watt one, so could well be responsible. I'm wondering whether it's safe to try running a power supply cable from my other better quality PC (let's call it PC2) without physically removing it from the case (just by sitting the boxes side by side) to test out whether the first PC will then boot up with the card in.

Proposed technique:
1. Power off both PCs
2. Connect cable from PC2's PSU to PC1's ATI 5770 card.
3. Power on PC2, to ensure power is provided to 5770 card prior to booting.
4. Power on PC1, and see if it works this time
5. If working, replace PC1's PSU for a better one.

Is the above safe to try? I don't want to fry anything! I would also prefer not to replace PC1's PSU with a better one and then find I still can't add the graphics card. Thanks!

If both PCs are plugged into the same power strip, I don't see why this would not be a useful and (likely) harmless test. The same power strip is important as this means they will share a ground, past any conditioning or protection.

To be 100% sure that the test will be complete, you could switch all the power connectors in the 5770 computer ("PC1") to the "PC2" power supply. While this will be more work, it will be a more complete indication of how PC1 will perform if you upgrade the power supply.


Note: I [heart] my 5770, and it runs most games at 1080p. When a game is giving me sub-40 fps, I just drop the resolution down to 1280x800 -- at that resolution the CPU becomes the only bottleneck.

Run power from one computer to another just for the graphics card? Dangerous.

Sure, it would work, but the computer powering the graphics card would have to be on whenever you want to use the computer with the 5770.

Remember that you have no idea what a power surge would do if you left it like that and a storm hit.

You spent $xxx on your 5770. You spend $XXX and $XXX on both computers. Is skimping out on a new power supply (even a 350W antec) worth all that?

I think that the OP is only going to run this odd power situation for a few hours. Once he has tested everything, and found out if the non-boot is due to his power situation, he will make a division about buying a new power supply.

If the computer will boot up without the card, but not with the card, it's absolutely 100% the power supply. No-name 350w supplies may not provide the necessary 12v amperage to run the card. Try to find that 12v amperage and let us know what it is, may be listed on the PSU.

I wouldn't recommend supplementing the existing power with a second power supply, the effects may be unpredictable. Either swap to computer 2's power supply and try and run it, or purchase a power supply with intention of returning it.

test 1: How about proving the 5770 is good to begin with? Pop it in your other PC and see if it works.

test 2: Regarding the PSU cable swapping...even with it on the same power strip, I'd be concerned with ground loop current causing issues (offset between psu1 and psu2 grounds). If you want to frankenstein it to prove psu1 is good or bad with the gpu inserted...I'd go with the plan for unplugging all of psu2's cables from PC2 and run the cables to power all of PC1.

- if the pc doesn't boot up in test 1: then you have a video card problem. (assuming the other PC PSU is able to handle the load)

- if the pc boots up fine in test 1 and not in test 2: then it's more likely to be a mobo issue. Maybe the card isn't seated well.

- if the pc boots fine in both tests, then it's your PSU.

How old is the motherboard? I've seen a couple of cases where an early PCIe motherboard has been unable to cooperate with some PCIe 2.0 graphics cards. They might boot into the operating system but there's never any picture.

Wow, a whole lot of extra responses arrived a few days after I stopped looking at the thread! Thanks for the replies!

The motherboard is as shown here: http://www.gigabyte.com/products/produc ... id=3009#sp

I can't see any version number for the PCIe slot, so maybe that means it's version 1.0?. I'm not sure what the card needs, but I'll try to research it.

Since writing the original post, I discovered the PSU is a non-standard size, so I'm going to need to get a new case before I can replace the PSU. Fortunately, I have one I can get hold of in about a month - it will be a new experience trying to shift my motherboard into it! I think I'll proceed with buying a PSU - one that's good quality and has got enough grunt to put into my next PC when I upgrade.

Again, thanks very much for your comments!