One PC, 2 PSUs ?

Situation- a PC with a 400W PSU, I'm thinking of adding a GPU which says it needs a 500W minimum PSU in the PC.

I've got a spare 300W, I was thinking of swapping that into the PC and running the GPU from the 400W one, probably mounted externally somehow- what it looks like is irrelevant .

I don't see why it shouldn't work, any opposing opinions? And what other precautions should I take, eg to make sure they both use the same 0v rail?

Don't know for sure but wonder if it could create some sort of imbalance having the card partially powered by one PSU and partially through the mobo on a second PSU. Sounds like a way to risk frying some electronics to me.

Think I would rather risk £30 on a cheap PSU that try running 2.

In reply to a post by ian72:

Think I would rather risk £30 on a cheap PSU that try running 2.

I'd think the risk of fried electronics is also quite high with a cheap PSU, but I take your point.

I'll probably get one of these if I go the "new PSU" route, I've used them before and like them.

That's why I said "risk £30" as a cheap PSU is a risk - although they should of course be reasonable and it is a 750W so has lots of headroom above what you need.

Personally I would probably spend more like £60 and get something even higher quality.

There are some comments on Toms Hardware relating to this. Sounds like there is a risk and someone is suggesting a bodge to get a common ground for the PSUs. Have to say if I valued my house I probably wouldn't risk the potential fire from something going wrong with a home bodge.

EDIT: The more I read the less having 2 PSUs looks like a good idea. There is a product called add2psu which purports to make this safer to do but as it costs $20 itself it seems buying a 500W PSU would be the far better option.

Edited by ian72 (Tue 28-Oct-14 09:26:19)

It may work but I don't have a good feeling about it. There is certainly a risk with it - cannot say exactly why but just gut feel.

Over the years I've found that gut feelings can give as good, and often better, guidance than rational analysis� fair enough, I'll resign myself to incrementing the number of redundant PSUs instead of decrementing it

Thanks both.

In reply to a post by billford:

Over the years I've found that gut feelings can give as good, and often better, guidance than rational analysis�

Or, your gut feel give you the answer in a few seconds. You then spend a day doing the analysis and calculations only to come up with an exact result that is remarkably close to the gut feel answer.

How will you switch the other PSU on? if it is not connected to a main board, you have to jump the connections.