I have a 580W PSU. Can it run a 5870 properly?
I have a Black Power LPG19. I can't find proper specs on it, but i think it's 580W. Could anyone help?

My current issue is that my comp is shutting down when playing games (either instant or after 5-10 mins), and sometimes freezing when booting.

Theoretically it should run on a 500W or greater PSU. But that would depend on PSU efficiency and the amperage on the 12V rails. The maximum power draw of the HD 5870 is 188W. That's approximately 15.67A on the 12V rail.

I doubt whether your PSU is able to provide that. I have never heard of a brand called Black Power.

Your best bet would be to get a good PSU like the Corsair 650TX as, with very high end components along with that card, system power requirements may exceed 550W. Else, you could look into the slightly cheaper Corsair 550VX.

Another option would be this.

So. That alternative thing. What exactly is that, and how does it work?

Read this article. Hopefully it will answer all your questions.

Thanks.

Also I found some info on my power supply. Don't know why it says Black Power on my psu, but the model name is lpg19. Searching for that on google finds it. I can't post a link yet.

What's the amperage on the 12V rail?

How do I check that? Multimeter?

Open up your cabinet. All specs should be listed at the side of the PSU.

There's a list of watts, and amps and stuff. Unsure what to look at. At 580 Watt and 12V it says 23Amps though.

there is your problem, a quality 500W PSU will have a lot more than 23A on the 12V rail. that's why its shutting down. you should have at least 30A on the 12V rail to run a 5870, and thats pushing it. get a PSU with 40A +

I absolutely agree. Just wondering though, does your PSU list multiple 12V values or just a single rail?