Good PC on crappy PSU?

AllMightySean

Honorable
Nov 29, 2013
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10,630
Hey I'm in the middle of upgrading my computer and I'm going to upgrade my GPU first.
I've got an old power supply, the SeaSonic SS-300ET (300 Watts Bronze certification) {LINK}

My complete build is: (and i know it has pretty bad bottle-necking)
-MSI A78M-E35 FM2+
-AMD 760K Richland Quad-Core 3.8 GHz Socket FM2 (not overclocked)
-PNY GTX 1060 3gb (also not overclocked)
-2 7200RPM hard drives
-2 4gb DDR3 1866 RAM
-And a few case fans + peripherals

I calculated my wattage from this guide {GUIDE} and I got ~290 Watts without headroom added on, can I use my 300W PSU while I save up enough to buy a new one without danger to my other parts?
 
Really just not a good idea. It could work, but it could also murder your PC. 500w PSU's really aren't too expensive I would definitely recommend picking one up before you throw that GPU in it, you could get a cheaper 1060 so you only have to pay maybe 20$-30$ more in total