I would like to buy a ATI Radeon 5850 for the upcomming Skyrim but i don't know if my power supply is powerful enough. The power supply came from a HP xw4300 Workstation. I read that it is recommended to have a 500w power supply for a Ati 5850 so i'm not sure if i should buy an other one
PC Specs :
Windows 7 Professional 64 bit
i3 CPU 560 (TDP 73w)
HP DPS-460CB A (Power Supply)
2x 2gb DDR3
2x 80gb SATA
For a system with a single Radeon HD 5850 graphics card a minimum of a 500 Watt or greater power supply with a combined +12 Volt continuous current rating of 26 Amps or greater and with at least two 6-pin PCI Express supplementary power connectors is recommended.
Your Delta Electronics, Inc. Model: DPS-460CB A power supply unit has a maximum combined +12 Volt continuous current rating of 31.5 Amps. What it lacks is two 6-pin PCI Express supplementary power connectors. You could use Molex to 6-pin PCI-E adapters but the problem is that the connector distribution on the +12 Volt rails is unknown. If all four Molex connectors are on the same rail you will trigger the rail's current limit protection circuit (+12VA@10A, +12VB@11A) shutting down the power supply unit.
A reference clocked Radeon HD 5850 graphics card itself may draw up to 12.6 Amps from the +12 Volt rail if you were to run a GPU stress testing app like FurMark or OCCT or if you were to overclock the graphics card. This would exceed the current limit of either rail +12VA or rail +12VB.
I would suggest a new power supply unit that actually has at least two PCI Express supplementary power connectors.
The HD5850 gets power from the motherboard and each of the PCI-E power connectors. The odds of ALL of these being the same rail when the PSU has more than one is basically nonexistent. It is not something he needs to worry about.
Delta is a good brand and 31.5a on the +12v rail should be fine for an HD5850, especially in a system with a low power i3.