How much power to feed miniITX PC?

Question

I need a compact power supply unit, but I don't know which picoPSU to buy to feed a Gigabyte GA-GC230D mini-IT motherboard + a 3.5" hard-disk, and a DVD burner used occasionally.

For the DC unit, would 90W be enough, or should I go for 120W or 150W?

What about the external AC adapter (60, 80, 102W)?

Answer 1

• Atom 230 = 25W
• DVD < 25W
• HDD < 30W

80W total. Lets say the PicoPSU is 80% efficient. No 90W will not be enough. 120 W will give you some headroom. You might want to consider Flash memory instead of a HDD; it will you a lot less power.

Answer 2

I'd certainly go for a larger one than you think you need. You could end up blowing an underrated PSU if everything is in use (HDD & DVD when installing or burning for example).

Another thing to bear in mind is that the various components might draw slightly more power than their rated values.

Answer 3

Regardless of rated draw, also keep in mind that if everything is idle, the PSU isn't pumping it's max output, either.