Apple Mac Pro Power Suppy EOL?

What is the simplest way to confirm power supply function? I have Apple Mac Pro 5,1 and experiencing intermittent boot failure / power up. I have also experienced random power off going into power saving.

Apple Hardware Test revealed no errors.

I am suspecting power supply as etiology. What is the best way to confirm this?

Checking the fitness of a power supply requires an oscilloscope and voltmeter, not something that can be done by everyone. You could try a visual inspection inside the PSU by removing it and opening it up.

Here's a possible replacement unit:
http://www.ebay.com/itm/Apple-Mac-P...562792?hash=item5427894e68:g:7b0AAOSwT4lWSqSs

I'd rule out other factors before opting for a replacement. From brief internet research, overheating caused by excessive dust buildup or other failing components (hard drives, RAM, CPU, etc.) can cause the machine to behave erratically.

My mac pro 2;1 suffered a power supply failure about 2 months ago, right at the 8 year mark. Defects can happen. A replacement for yours, used, is about $200 at the cheapest on eBay. New ones don't really exist anymore as the cheese grater mac pro is EOL.

You could open up the PSU and inspect for any bulging/busted/loose capacitors. If you find such, i'd be more than happy to help you locate replacements.

GLTY

If you need capacitors or other components to repair your power supply, I'd recommend www.mouser.com as they don't have a minimum order on most in-stock items. The only downside to them is they stiff you on shipping, with 1 lb being the minimum shipping weight. Shipping is generally $5-7 unless you get a lot of stuff or are getting some larger items.

There are a couple other sites like Digikey, but I find they don't have as good of a selection of parts. Like they'll have a specific farad and voltage rating, but they'll only have one or two dimensional sizes that won't fit where you need them to.