Ati HD 5850 1gb and my PSU?

You are getting a little close to it's max. Sure a 650w can run a i7 with two 9800gt in sli but a 5850 with a 600w maybe. Go ahead and get the card and if the volts on the 12v rail dip below 11.4v get a new psu. If the psu makes all sorts of strange sounds while in use get a new on.
 

Gulli

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Google doesn't give us the max combined wattage on the 12V rails (should be on the label), so there's no way to tell whether it'll work or not.

A 450W Corsair PSU will power your rig with a 5850, but this Thermaltake 600W might not, it all depends on the max combined wattage on the 12V rails.
 

Gulli

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It uses 40W more and considering the fact you should always stay under 80% of the max combined 12V rails load, you need 50W more on the 12V rails.
 

Gulli

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It depends on the max combined wattage of those 12V rails, this could be less that 2X19A*12V = 456, it also has to have two PCI-E connectors.
 

hopkiller

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Use this http://extreme.outervision.com/psucalculatorlite.jsp. It will give a general number that would need to run the rig. If yous is above the numbers it should work. But if it is borderline, I would be careful. Worst comes to worst, you buy a larger power supply.
 

Gulli

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It's fairly easy actually:

[130W (CPU) + 15W (hard drive and fans) + 20W (DVD-RW) + 150W (HD 5850) or 190W (HD 5870)]*(10/8) = 400W (34amps) or 450W (38 amps) combined max wattage of the 12V rails, you also need two PCI-E connectors.