5870 Future Crossfire

TMLewiss

Junior Member
Dec 25, 2009
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I am currently building a new system, as my gcard just died a few days ago. I wanted to wait another 3 months, but that's life.

In any case, I am building a new Core i7 and 5870 build. I want to have it setup to where I can Crossfire in a year or two. So I would like to have it ready for just plug and play. My question is, does anyone have a recommendation on a PSU? I am not great when it comes to hardware, and I really don't want to order something that won't hold up.

From research I have pretty much seen that I will need around 950 -1000 watts for full load on my system.

Here is the system I am building:

G.SKILL 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Triple Channel Kit Desktop Memory Model F3-12800CL8TU-6GBPI - Retail

ASUS EAH5870/2DIS/1GD5/A Radeon HD 5870 (Cypress XT) 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported ... - Retail

COOLER MASTER HAF 932 RC-932-KKN1-GP Black Steel ATX Full Tower Computer Case - Retail

ASUS P6T LGA 1366 Intel X58 ATX Intel Motherboard - Retail

Intel Core i7-920 Bloomfield 2.66GHz LGA 1366 130W Quad-Core Processor Model BX80601920 - Retail

COOLER MASTER Hyper 212 Plus Intel Core i5 & Intel Core i7 compatible RR-B10-212P-G1 120mm "heatpipe direct contact" Long ... - Retail

As well as old parts:

3xSATA
TV Tuner
Sound Card
DVD+-RW
8 USB Devices

I do actually use a lot of these devices at full load often. I watch video on 1 monitor, while playing a game on the other and my tuner records TV... That pretty much puts everything but 4 of the USB devices into use... See why I want 950 -1000 watts? I also plan to OC my i7 to 3.2 - 3.5 in the future.

So, after that long post, if your still here... Do you have any suggestions on a PSU that would be good for me? I really don't want to go over $200, though if I need to, I will.
 
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smackababy

Lifer
Oct 30, 2008
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How are you figuring 900+ watts? I think the 5870 peaks under 200, so that is like 400w for both. You don't need another 500w to overclock an i7. Just a consideration.
 

TMLewiss

Junior Member
Dec 25, 2009
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From what I have read, the load of the 5870s is 450w under full load. Then an OC i7, plus 2 PCI slots running, 3x SATA drives running and 4x 120mm+ fans running and at least 4x USB devices running. And yes, those all run at the same time about 4 hours a day on my PC. Then another 10+ hours of 80% of that. I just don't want to be screwed getting an 850 watt and coming up short sometime. Most PSU calcs tell me to get 950 minimum. Extreme tells me 600-850 depending on the capacitor aging.
 

TMLewiss

Junior Member
Dec 25, 2009
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Now I am choosing between:

Corsair 1000HX

Enermax Revolution85+ 1050


They both look nice. The Corsair though, is 2x500 watts. I don't know if this would pose a problem later on? I don't know how the PSU is handled. The enermax is a single 1050 watts.

Both are good brands with good reviews. Any suggestions?
 

HOOfan 1

Platinum Member
Sep 2, 2007
2,337
15
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From what I have read, the load of the 5870s is 450w under full load.

Not even close...more like 130W under full load. 450W would put it way out of spec. An entire system with the 5870 may use 450W.

For the system you are considering 850W and above is more than enough.
 
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smackababy

Lifer
Oct 30, 2008
27,024
79
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I believe the max watts those cards can pull (using 1 6 pin and 1 8 pin connector) is 225W. I might be wrong about this, but it is nowhere near 400.

I would suggest at high quality 750w. Now, you can purchase whatever you like, I am just suggesting from my experience.
 

Ayah

Platinum Member
Jan 1, 2006
2,512
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The rated maximum is 75W from the bus, 75W for each 6 pin connector (there are 2). For a total of 225W rated maximum.

Since there is nothing preventing a card from drawing more than 75W per 6-pin connector, there really is no limit other than the limit of available 12v power from the PSU on the rail(s) supplying those connectors. And of course your cooling capacity will limit the voltage you can supply to the GPU without melting it and everything around it.
 

smackababy

Lifer
Oct 30, 2008
27,024
79
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Even if there is no actual limit, nobody would release a card reference that pulled more than that. At least, I'd hope not.

And are you sure about the PSU allowing such voltage from each rail. I know if you exceed the amp limit per rail or overall, it will shut down.
 

HOOfan 1

Platinum Member
Sep 2, 2007
2,337
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Even if there is no actual limit, nobody would release a card reference that pulled more than that. At least, I'd hope not.

And are you sure about the PSU allowing such voltage from each rail. I know if you exceed the amp limit per rail or overall, it will shut down.

The 75W and 150W specifications are set by PCI-E SIG. Those limits have nothing to do with the PSU. Rail limits are not designed around the PCI-E SIG specifications....in fact they should be far above those limits.
 

Ayah

Platinum Member
Jan 1, 2006
2,512
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You have these ultra-large 1200W PSUs with a single 12v rail that can provide over 80A. You can definitely draw more than 20A off that PSU without it blinking. The most limiting factor will probably be the wiring.