pico psu with 24 pin + 8 pin?

[iamnoobplzhelp]

I am trying to optimize my rigs, and I've moved to using server PSUs to power the cards. Instead of a normal ATX PSU for the motherboard and CPU, I've read some posts about people using Pico PSUs, but I haven't been able find many online. Which ones are people using? Are they cheaper than just a cheap ATX PSU?

[mikhan]

picopsu
aliexpress.com/wholesale?ltype=wholesale&d=y&origin=y&isViewCP=y&catId=0&initiative_id=SB_20170608180144&SearchText=picopsu&blanktest=0&tc=af
it's just a dc-dc converter (12v from server psu to 12v, 5 and 3v atx + 4/8pin cpu + some molex & sata)