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Enough power for 7970?

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December 23, 2011 11:01:21 AM

Dear All,

I will be getting an AMD 7970 as a replacement for my aging AMD 5850. I am a little concerned if my current 650W PSU will be able to deliver sufficient power however, since I am running an i5 750 @4Ghz cooled by Coolit ECO, four sticks of 1.65V DDR3 Corsair (8 GB in total), three 240mm fans and 2 additional 120mm fans (HAF 932 Case).

I am being told that the i5 750 clocked at 4Ghz consumes approx. 250W at full load, and the 7970 is estimated to consume circa 230 - 250W. The question that I wish I then is: is the 'remaining' 150W sufficient to operate the DDR3 RAM modules, the motherboard, Coolit ECO, fans etc?

Thank you in advance :) 

Luke

More about : power 7970

December 23, 2011 11:14:23 AM

650W PSU would be more than enough.
a c 87 ) Power supply
December 23, 2011 11:31:19 AM

The link shows a system with an i5-750, GTX 260, etc (page 6 for test system) using 155W on stock and 238W at peak load from the wall with the CPU at 4GHz:
http://www.tomshardware.com/reviews/core-i5-750-overclo...

So based on that I don't believe that the CPU by itself would consume 250W.

The Anandtech review shows a system with a Sandy Bridge E processor (which is more power hungry than an i5-750) using ~390W under Metro2033 at the wall.
http://www.anandtech.com/show/5261/amd-radeon-hd-7970-r...

So vitornob is correct: 650W is plenty for a system with a 7970.
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December 23, 2011 12:57:05 PM

Thank you both for the responses, I appreciate it.
a b ) Power supply
December 23, 2011 1:28:35 PM

depends what psu you got exactly
December 23, 2011 1:44:43 PM

obsidian86 said:
depends what psu you got exactly


I've got an old (2006 -2007) Seasonic 650W PSU - it got great reviews,and it wasn't too expensive, so it seemed like a good purchase. That said, I know little about PSUs.
a c 111 ) Power supply
a b À AMD
December 23, 2011 2:51:52 PM

We don't know how much power is requiered atm, but im pretty sure your psu should do it.
a c 1200 ) Power supply
a b À AMD
December 23, 2011 4:11:21 PM

For a system using a single Radeon HD 7970 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 36 Amps or greater and have at least one 6-pin and one 8-pin PCI Express supplementary power connectors.

A Seasonic 650W PSU usually has a +12 Volt continuous current rating of 52 Amps or greater so it's electrically more than sufficient. Whether or not you have the appropriate PCI Express power connectors, only you know, since you didn't provide the Seasonic model number.
a b ) Power supply
a c 121 À AMD
December 23, 2011 4:19:21 PM

The HD 7970 peaks at 210w.

An overclocked i5-750 @ 4.0GHz will not consume 250w, it would burn out long before then. I'm guessing probably around 90w 95w.
December 23, 2011 4:34:06 PM

jaguarskx said:
The HD 7970 peaks at 210w.

An overclocked i5-750 @ 4.0GHz will not consume 250w, it would burn out long before then. I'm guessing probably around 90w 95w.


Right, so the number I'm getting (250w) is for the entire computer and not only the processor? i.e. does the link posted by Silvune (http://www.tomshardware.com/review [...] 38-11.html) refer to an entire computer including all the various components ?
December 23, 2011 4:36:49 PM

ko888 said:
For a system using a single Radeon HD 7970 graphics card AMD specifies a minimum of a 500 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 36 Amps or greater and have at least one 6-pin and one 8-pin PCI Express supplementary power connectors.

A Seasonic 650W PSU usually has a +12 Volt continuous current rating of 52 Amps or greater so it's electrically more than sufficient. Whether or not you have the appropriate PCI Express power connectors, only you know, since you didn't provide the Seasonic model number.
edit: the PSU has four 12V rails, each rated 18A, does this suffice?

Thank you for the detailed info. I would check the model number, but unfortunately the sticker on the side of the PSU with all the detailed info faces the inside of the computer case - I would have to take it out in order to provide the number.
December 23, 2011 4:41:53 PM

Do you know your PSU connectors? If so, you can easily see if you have the required 6 pin and 6+2 pin connectors.
December 23, 2011 4:51:00 PM

ilikemacandpc said:
Do you know your PSU connectors? If so, you can easily see if you have the required 6 pin and 6+2 pin connectors.


Yes, the PSU has a 6+2 and a 6 pin connector.
a c 1200 ) Power supply
a b À AMD
December 23, 2011 5:11:00 PM

Luer said:
edit: the PSU has four 12V rails, each rated 18A, does this suffice?

Thank you for the detailed info. I would check the model number, but unfortunately the sticker on the side of the PSU with all the detailed info faces the inside of the computer case - I would have to take it out in order to provide the number.

The answer is yes.

The "combined +12 Volt continuous current rating" part of the info, that I provided, handles the multiple +12V rail PSUs like yours. Seasonic usually properly distributes the PCIe connector cables across the +12V rails so you shouldn't run into any load balancing problems.
December 23, 2011 5:39:14 PM

The 7970 is very efficient I would not fret about it the 650watt being enough juice.
a c 87 ) Power supply
December 23, 2011 5:57:23 PM

Luer said:
Right, so the number I'm getting (250w) is for the entire computer and not only the processor? i.e. does the link posted by Silvune (http://www.tomshardware.com/review [...] 38-11.html) refer to an entire computer including all the various components ?

Yes that link refers to the power consumption of the entire system.
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