Psu built into mobo?

[Piemanfood]

So I've got a weird question for you guys. So I opened my prebuilt desktop to do some cleaning and I took the whole mobo out to clean it with some compressed air. For as much as I looked I didn't see a psu in the case, whether I didn't look in the right spot or something I didn't see one so i was wondering if some mobos have a power supply built into it. Another thing is there are no pci or pci-e slots anywhere on the board.

[Gale]

Could you post a picture to show us?

[Sakkura]

The motherboard can easily have DC-DC regulators on it, but the conversion from AC to DC would hardly fit on a motherboard. It would be one hell of a Frankenstein thing. But if the motherboard really doesn't have any expansion slots, I suppose anything is possible. Anyway, where does the power plug in?

[W-L]

19 minutes ago, Piemanfood said:

So I've got a weird question for you guys. So I opened my prebuilt desktop to do some cleaning and I took the whole mobo out to clean it with some compressed air. For as much as I looked I didn't see a psu in the case, whether I didn't look in the right spot or something I didn't see one so i was wondering if some mobos have a power supply built into it. Another thing is there are no pci or pci-e slots anywhere on the board.

Well the power supply isn't exactly built in 100% there are some that use a AC to DC adapters that plug directly into the motherboard and get all their power through that one connector. On the motherboard there will be a portion of the board that breaks out and steps down the voltages to the require 5V and etc. They are usually low power systems or boards that have the option to be low powered ones. 

[alexhelvetica]

The PC will use an external PSU like a laptop. I have a crappy HP prebuilt with an LGA 1155 (Ivy Bridge) Celeron which has a laptop power supply, they only do it with low power crap CPUs, the max that mobo can support is a lowpower i3.

[manikyath]

some (especially cheaper) prebuilts use a laptop-style power brick that plugs directly into the motherboard, and the motherboard contains all the hardware required to turn that (usually 19 volts) input into +12v and +5v.

 

in some less extreme cases (HP does this for their office computers, and dell and acer have the same dealio going on) will have a 12 volt only power supply, which plugs into the motherboard with a limited number of -easier to plug and unplug- connectors. HP does this to allow office computers to get a power supply swap in literally under a minute (good luck unplugging a 24-pin in that time) and dell and acer probably do it for the cheap.

 

EDIT: for those who wonder what it looks like, carey holzman has a rather hilarous, quite cynical review of a $350 HP computer that has the laptop power brick going on:

 

 

[incarnate]

It most likely uses a power brick like a laptop or game console