Downsides to a larger power supply

[cjswans]

Hello,
I'm working on my second build and have probably a simple question but I can't find a definitive answer for it. Are there disadvantages to having a too-large power supply? The power supply I'm looking at, the Seasonic X series is cheaper at 750 w than at 650 w due to the larger one being on sale. I'm pretty sure that I don't need that much power, as I'm planning on building with a z-77 board of some stripe, an i5-3570k, a single geforce 670, and one ssd/one hdd, and it only came out to ~530w on the power supply calculator i used, but I have a hard time passing up the better deal. I might conveivably go SLI at some point, but not any time soon. Are there any disadvantages to having a power supply that is overkill, or will that extra power simply not be used?

 

[DJDeCiBeL]

A PSU with more wattage than you need is just fine, it's just less efficient at the lower wattages that you will actually use. It will only use as much as the system requires, plus the amount lost due to inefficiency.

 

[amuffin]

You actually have a good advantage, you have enough to run triple SLI 670.

 

[cjswans]

Thanks for the very helpful answers! I think I'm going to go with the 750X. Just a follow-up question - my case (Rosewill future) suggests that I install the PSU upside down, with the fan facing the bottom of the case. This doesn't make sense to me, as the fan would just be blowing nowhere. Is there a reason I should do this, or should I just put it in fan facing up?

 

[cjswans]

Best answer selected by cjswans.

 

[dudewitbow]

Thanks for the very helpful answers! I think I'm going to go with the 750X. Just a follow-up question - my case (Rosewill future) suggests that I install the PSU upside down, with the fan facing the bottom of the case. This doesn't make sense to me, as the fan would just be blowing nowhere. Is there a reason I should do this, or should I just put it in fan facing up?

I own the case, the case itself has pegs that are a bit under one inch off the ground, so its blowing air through the bottom of the case. which is outside the case, so the inside of the case does not get warm

 

[amuffin]

The fan is sucking in cool air to the components in the PSU.

 

[cjswans]

I own the case, the case itself has pegs that are a bit under one inch off the ground, so its blowing air through the bottom of the case. which is outside the case, so the inside of the case does not get warm

ah, makes total sense now. thanks much for answering!