Have a 20pin PSU, can it handle a 24 pin adaptor?

[DermicSavage]

I dont know power supply system nearly as well as everything else, but I have just gotten a DFI board(Lanparty RDX200) and am left with no money left to buy a new power supply. From what it looks liek with the adaptors, they just split two of the 5v and ground rails. Which to my understanding will basically half the amps going down each split of the rail, correct?
So that is to say that higher quality power supplies could withstand the extra stress added by the 24 pin adaptors?

I am currently running an Antec Trupower 550W, here's the spec off the sticker for the amps on the rails:
+5v: 40A
+12v: 30A
+3.3v: 32A
-5v: .05A
-12v: 1A
+5V 5B(wtf?): 2A

Can my PSU take it? or would I be better off risking running without the adaptor entirely?

 

[AssMan]

Well all the DFI NF4 boards require a 24 pin PSU 480 watts or better. I would think it'd be the same for that one too so it will probably be fine but might cause problems.