Hi guys I recently ordered a sapphire r9 280x GPU and I'm now starting to worry about my psu I have a 500w (30A 12v) psu can't remember the brand and wondering wether that will be enough to power my r9 289x I only use 150-200W on max load right now and I'm not planning to OC at the moment and I heard that 750w isn't necessarily needed people run that card with other 500w psu's so do you guys think I will have any issues and what happens if a psu isn't strong enough to power the machine(only bought the power supply last year)
You might have a bit of trouble. 30A at 12v is only 360watts. Anyways, it looks like the 280xs generally are in the 230-240 watt range. Generally you want to shoot for total power consumption at about half load on your PSU. So if your global power consuption is going to be about 400 watts off a 500 watt power supply, youre pushing your luck. being that your 12v rail is only 360 watts, that could be a disaster.
I'd say that if you can find a 80+ psu with around 42-48 Amps on the 12v rail you will be well safe. That would give you enough headroom to overclock a bit, deal with any spikes or surges and can take into account aging