Velinzor :
Rogue Leader :
You need to buy a new PSU for 2 reasons. 1 is that PSU is a piece of junk. Its underpowered for an R9 290 (650w is reccomended although not 100% required if you have a REALLY GOOD PSU, which you don't). 2 is that it definitely does not have the right connector.
Buy yourself an XFX, Seasonic, or EVGA 550w PSU. Where are you located I can drop some links for you.
In canada ontario but I plan on going to a PC store today, im buying a AMD Athlon 860k with the R9 290 but i didn't think i was going to need a whole new power supply
OK well while you are there look for specifically the XFX TS 650w, or EVGA 750B2 (overkill but generally an excellent price), Seasonic SII 620. Do not buy some no name brand, do not buy a Corsair CX series PSU. If these aren't available then Antec is often a good choice, or another XFX, Seasonic, or EVGA. As long as they are over 550w (650 is preferable).