I've done a GPU rig powered with a HP DPS 1200 FB-A server psu and a pico psu. It was a great setup. You can find a pico psu for better price in Aliexpress, for example.

Edit: This was the one that I bought from Aliexpress https://m.aliexpress.com/item/32828439849.html?spm=a2g0n.orderlist-amp.item.32828439849&aff_trace_key=&aff_platform=msite&m_page_id=1141amp-jekuphr4TI0-fX27zpw3aQ1595452733747&browser_id=92c5052f659640e6b7d2cfbd9fab77d4&is_c=Y