I'm getting conflicting information from our suppliers of Routerboards. I want to know if this hardware configuration is supposed to work:

Routerboard 532
Daugterboard that can attach two additional mini PCI slots
Routerboard.com 48V power supply

I want to load it with three AR5213 (CM9s) and one SR5 card. Total of four cards.

My one supplier says it's fine but the other supplier says you can't use the SR5 card with so many AR5213s because you'll have power issues.

this will not work , this topic has already being treated. You cannot use the SR-5 with three other CM9 radios too much current draw. Best bet is to leave the SR5 out of the mix.
Always remember that you cannot eat your cake and have it , a chap with just one AR5213 (CM9s) on his RB532 will have a more stable and efficient network, than yours with all those cards competing for limited processor and memory.

regards