Readynas Pro RNDP6310-100NAS - Power Supply

The 6-bay legacy NAS all use an standard SFX format suppply, except the cable is longer.  I've not really found one I like since Seasonic stopped production of the original.  There is someone on eBay who advertises supplies already modified to fit (proper cable length and enough 4-pin Molex connectors), but that one may be what some have had problems with when it comes to the 3.3V (getting warnings about low voltage).

If you just want to offload the data, a standard ATX supply can be used externally, though you may need to get some SATA to Molex 4-pin (PATA power) adapters to have enough to plug into the SATA backplane (there are 3, though connecting 2 is probably enough for short term data offloading).