So recently Iv'e been trying to wrapp my head around why my ATI 5830 will not work with my Mobo, yett oddly enough it works perfectly fine with my wifes mobo.
To start off, My Computer originaly had an Asus GT550 Ti, but I noticed performance issues. So I replaced it with the 5830 from my wifes computer. It worked at first, then all the sudden it wouldnt. Onboard video works just fine aswell.
550Ti > Works in both our computer's
5830> Only works in my wifes computer
I have reset my bios, checked the voltages of my 12v rails, set my resolution to 800x600 just to see if it was my monitor not accepting the signal and still nothing. Set my bios chipsettings to accept PCI-E.
I'm leaning towords a bad PCI-E slot.
Apevia Warlock 900watt
enermax tomohawk II 450 watt
I am guessing your Radeon HD 5830 is a PCI-e 2.1 card. Some motherboards with PCI-e 1.0 or 1.1 have issues with these types of cards because the PCI-e standard may not have been properly implemented. Sometimes a BIOS update can correct the issue, sometime it will not.
Both of your motherboards have PCI-e 1.0 or 1.1 slots. Try updating the BIOS of the M5A78L-M LX motherboard. You can download a BIOS update and installer from Asus' website. This may or may not fix the issue.