Why can't I run dual 250 Power Supplies?

[Wangel]

I'm modifying a case already, so why can't I run dual 200 or 250 watt power supplies. The advantage would be twice a many power connectors. The 200 and 250 watt power supplies are very cheap $20 or $25 each. Also, if one power supply went out, I would be able to switch it and continue to run. And the last reason is that I would have two fans sucking air out of the case. What are the downsides to running two power supplies. Of course you must have a large enough case to contain 2 power supplies.

 

[Big Lar]

I can't see any real downside to running 2 supplies, of course I am bias, as I have been doing that for a longgggggg time

 

[dman]

My suspected Disadvantages:

1) Need a bigger case that will allow mounting of 2 supplies (Duh).
2) Need to wire up a/the power switch for the second supply (atx).
2b) Need them to both turn on at the same time... or else you may have sync problems starting the system board with one supply and the accessories w/ the other.
3) You may not be getting the power to where it's needed...
EX: There are 3.3v 5v and 12v lines in a power supply. If all your motherboard items are using the 3.3v power and the supply isn't enough to satsify that need then adding a second supply isn't going to help because you won't be providing power to the motherboard, just to your peripherals. (Of course, if any of you perphs are using 3.3v and you move them to the new supply that leaves more power available to the motherboard items... but... now you are managing the power).
4) You have the potential for ground loops having a motherboard powered off of one supply and accessories on another. I don't think this would cause problems, but, it is a remote possibility.
5) For the extra $20-25 you paid for the 250w supply you could have spent extra to get a case w/ a 300w supply and not had to deal w/ any of this.



In summary, basically no huge disadvantages that I can see, but, kind of a pain in the a-double-s to manage.

 

[lhampel]

High End servers use dual power supplies. (sometimes triple)
But what would those guys know about advantages? (plenty)

 

[ericd]

Well for one thing servers use special power supplies that are designed to be operated in that way. Secondly by buying cheap 200 watt power supplies you are increasing your chances of failure. An Enermax, PCP&C, Sparkle, or PowerMan would probably last twice as long as two cheap 200 put together. Secondly a cheap power supply is not going to be giving very good power to your components. This may never cause a problem but then again it could cause a lot of problems too.

Eric

 

[damien6]

<< High End servers use dual power supplies. (sometimes triple) But what would those guys know about advantages? (plenty) >>




Actually, most high ends servers use more than just two or three P/S but many severs/workstations do have dual P/S setups. The ones you're referring to are called redundant P/S and there are slight differences from those setups, to just tieing up two average P/S. Those redundant P/S either have a built in power sharing/regulators or there should be one attached to the interior of the case itself. (power sharing board)

I'm no electrical expert or anything and I don't know how well the (each single relevant) parts are in handling the extra loads but it would truely suck if it gave away in a short period of time. Another thing to look at is, having extra P/S would most likely create more noise + heat in the case than a single higher output P/S.