Power supply HELP!!

Well, the difference is pretty significant. Based on this PSU ranking list http://www.eggxpert.com/forums/thread/323050.aspx the CM real power pro is higher
quality, Tier 2 PSU, while the CM Silent Pro is a tier 3. You should absolutely choose
the Real Power Pro 850 if you're only considering those two PSU's.

However, if you're open to suggestion, I would recommend a PSU from Corsair or Seasonic. For the same price--or cheaper than the two Cooler Master's above--you could get a high quality Corsair, Seasonic, or even Antec PSU that I would trust more than the Cooler Master PSU's. You really want a trusted, reliable PSU to power that system. You have high quality components and they will need high quality power to feed them. And you don't need 850 watts with that system either. A 550 watt PSU from these brands should be more than sufficient to power your system in a single GPU configuration. If you think you might want to use dual GPU's in the future, I would get a 650-750 watt PSU. It would be overkill now, but be just what the Dr. ordered if you want to crossfire/SLI later on.

Are those the only choices you have for a power supply?

The silent pro 850 has one large +12 volt rail while the real power pro 850 has mutiple +12 volt rails.

The silent pro 850 can deliver a maximum of 894 watts at 48.9C. The real power pro 850 has heavy duty parts and can actually deliver 1,000 watts at 50C.

Both power supplies are adequate but they have problems. For example the over power protection (OPP) is missing. That would suggest Coolermaster took shortcuts to reduce costs. There are a few more problems so I cannot recommend either one.

You listed 4 different video cards but neglected to mention how many video cards you are going to install. If you are only going to install one video card, then an 850 watt power supply is not necessary. It is overkill.

You listed the ATI Radeon HD 5970. Currently it is the world's fastest video card.

Here are the official power requirements for ATI Radeon™ HD 5970 video card.


ATI Radeon™ HD5970 System Requirements:

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard

650 Watt or greater power supply with one 75 watt, 6-pin and one 150 watt, 8-pin PCI Express® power connectors

850 Watt or greater power supply with two 75 watt 6-pin, and two 150 watt, 8-pin, PCI Express connectors for ATI CrossFireX™ technology in dual mode

The power supply recommendations are for an entire pc system.

Corsair and Seasonic are two of the brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty.

Hey man Thank you for your reply. I am going to install GTX 260 as physx processor if i purchase GTX 480 or 470 otherwise i would get only HD 5970. And in future i would be looking forward to SLI/Crossfire. Perhaps u can recommend me a good PSU which can handle two HD 5970.

I understood , i would be using GTX 260 as physx processor and other one will be 480/470 or HD 5970. That's why i need a more powerful supplier. Please recommend me a good supplier.

Other than not including Antec with Corsair and Seasonic (Antec fanboy here  ; supported by reviews), JohnnyLucky provided a very complete answer. I hope Coolermaster isn't your only PSU choice. Since you're planning two video cards (even if one is for PhysX), you might want up to 850W even if only one of them is a HD5970. In your place, I think I'd choose this one: http://www.newegg.com/Product/Product.aspx?Item=N82E168... for $170.
CORSAIR CMPSU-850HX 850W ATX12V 2.3 / EPS12V 2.91 80 PLUS SILVER Certified Modular Active PFC Power Supply. It is 80+ Silver, and modular, two features I think you'll want. Being an Antec fanboy doesn't prevent me from recognizing that Antec's offerings in that range are 80+ bronze, vs. 80+ silver for the Corsair.
Unless / until nVidia changes its tune, you may need to play games with mixed driver versions to get PhysX to work if you have an ATi card in your machine; just something else to keep in mind.

jtt283 - I always mention Antec in my "psu rule of thumb" that I post quite often. I didn't include Antec as I wasn't sure what the OP intended for video cards. It looked like the OP might want to go very high end.