Hi newcomer and welcome to the Tom's hardware forum.

Here are the system requirements for the 4870

ATI Radeon™ HD 4870 Series System Requirements

ATI Radeon™ HD 4870 System Requirements
PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard
500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended (600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode)
Certified power supplies are recommended. Refer to http://ati.amd.com/certifiedPSU for a list of Certified products
Minimum 1GB of system memory
Installation software requires CD-ROM drive
DVD playback requires DVD drive
Blu-ray™ playback requires Blu-ray drive
For a complete ATI CrossFireX™ system, a second ATI Radeon™ HD 4870 graphics card, an ATI CrossFireX Ready motherboard and one ATI CrossFireX Bridge Interconnect cable per graphics card (included) are required


The recommended PSU is for the entire system.

U can go with this Antec 650W are more that the PSU that u need, but can handle ur future upgrades.

Coolermaster don't makes a very good PSUs, so, try to avoid it.
 

Henry Chinaski

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If you are thinking about NOT to do CF, here you have some good options:

ANTEC Earthwatts 500W (by Delta Electronics)
CORSAIR VX550 550W (by CWT)
ENERMAX ECO80+ II 500W
SEASONIC S12II Bronze 520 W
THERMALTAKE Toughpower QFan 500W (by CWT)

All of them are high quality PSUs at a good price.
 

Henry Chinaski

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If you do not want to discard the possibility of a future cf, go for one of the following PSUs:

ANTEC TRUEPOWER NEW 650W (by Delta Electronics) (modular)
CORSAIR HX650 (by Seasonic) (modular)
CORSAIR TX750 (by CWT)
ENERMAX Liberty Eco II 620W CrossFireX (modular)
ENERMAX Pro82+ II 625W CrossFireX
THERMALTAKE Toughpower XT 675W (by CWT) (modular)
 

Henry Chinaski

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If you are thinking about doing CF, don't buy it. It hasn't enough PCIe conectors. You need four 6-pin connectors and it has only two. You will be forced to use Molex to PCIe adapters, which is NOT recommended. So even if your PSU has MORE than ample power for your CF4870, since it doesn't come with all of the appropriate connectors, go for another power supply.