Power Supply for my new Core I7 system

PSUs: The source of DC power for all components in the PC & often a big noise source.

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Immersion
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Power Supply for my new Core I7 system

Post by Immersion » Tue Dec 30, 2008 3:09 pm

Today I own a very good power supply, a Seasonic S12 600W which I am very happy with (very silent). However for this new system I have calculated with a calculator (http://www.extreme.outervision.com/PSUEngine) that my system will use at least 509w when the CPU is overclocked to 3.5 GHZ. At most I have a margin of 89W , it is not much, I did however notice that the Graphic card takes about 100w (Gigabyte Radeon HD4850), this is quite a lot, I am not sure how constant that 100w usage is for the graphic card, but if it is constantly 100W, then I might consider to upgrade to a new Power Supply.

What do you guys think, what margins in your power supply is reasonable ?

If you absolutely think I need a new PSU, please suggest me the most stable and efficient and silent Power supplies.

tehfire
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Post by tehfire » Tue Dec 30, 2008 7:23 pm

I can't say for certain unless you tell me your entire power configuration, but your current power supply should be more than sufficient. My friend's dual-GPU, overclocked E8400 rig only uses 390W peak, so you should have plenty of headroom.

Immersion
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Post by Immersion » Tue Dec 30, 2008 7:26 pm

tehfire wrote:I can't say for certain unless you tell me your entire power configuration, but your current power supply should be more than sufficient. My friend's dual-GPU, overclocked E8400 rig only uses 390W peak, so you should have plenty of headroom.
If we should assume my calculations above is correct I got 80w of headroom, that can't be the ideal for an power supply ?
I can also imagine the closer and closer it gets to the full capacity of 600w the more noisy it will get.

maf718
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Post by maf718 » Tue Dec 30, 2008 8:26 pm

Hi, the graphics card will probably take about 40W at idle and only over 100W at full load.

I very much doubt your system, even when overclocked, will draw anything like 509W - in my experience these power supply calculaters overestimate the wattage you are going to need. If I had to guess I would say 100W idle and maybe 300W load for the entire system. Also, a Seasonic is a lot different to an el cheapo no-name PSU.

Immersion
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Post by Immersion » Tue Dec 30, 2008 8:43 pm

maf718 wrote:Hi, the graphics card will probably take about 40W at idle and only over 100W at full load.

I very much doubt your system, even when overclocked, will draw anything like 509W - in my experience these power supply calculaters overestimate the wattage you are going to need. If I had to guess I would say 100W idle and maybe 300W load for the entire system. Also, a Seasonic is a lot different to an el cheapo no-name PSU.
Well I must say I really hope you are right, even though 300w sounds maybe too optimistic :)

I read up the review on the graphic card
http://www.bit-tech.net/hardware/2008/1 ... 850-1gb/10

It turns out that the power consumption is 170w during idle and 273w during load. 273w is almost half of the 600 Capacity of my PSU.

according to this article an core i7 920 clocked to 3.5GHZ will use 211W.
http://enthusiast.hardocp.com/article.h ... VzaWFzdA==

So power Consumption for CPU and Graphic card together would be 273w+211w =484w? if I shall believe this numbers, and then is not hard drives or anything else included in the calculation.

maf718
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Post by maf718 » Tue Dec 30, 2008 10:55 pm

I think the power consumption in that Bit-tech article is for the whole system, so you can't really add them together. I just checked SPCR's review of the Core i7 and the power consumption for a 3.2Ghz i7 with a GTX260 graphics card (which uses more power than a 4850) is 367W for the whole system. That's with Prime 95 and Furmark running at the same time which simulates a higher load than you could realistically get in normal use. http://www.silentpcreview.com/article884-page5.html

I guess 300W was too optimistic but it's in the ball-park :)

Immersion
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Post by Immersion » Wed Dec 31, 2008 7:56 pm

maf718 wrote:I think the power consumption in that Bit-tech article is for the whole system, so you can't really add them together. I just checked SPCR's review of the Core i7 and the power consumption for a 3.2Ghz i7 with a GTX260 graphics card (which uses more power than a 4850) is 367W for the whole system. That's with Prime 95 and Furmark running at the same time which simulates a higher load than you could realistically get in normal use. http://www.silentpcreview.com/article884-page5.html

I guess 300W was too optimistic but it's in the ball-park :)
Yes I Think you are right, 273w for a graphic card of that kind seem not reasonable. I think I might be enough with my seasonic s12 600w.

Redzo
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Post by Redzo » Thu Jan 01, 2009 5:53 am

Just as maf718 wrote, those tech bit numbers are for a whole system not just vid card.
Immersion: your system will not brake 450W fully loaded and overclocked. Your PSU will do just fine.

Immersion
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Post by Immersion » Thu Jan 01, 2009 8:07 am

Redzo wrote:Just as maf718 wrote, those tech bit numbers are for a whole system not just vid card.
Immersion: your system will not brake 450W fully loaded and overclocked. Your PSU will do just fine.
Yeah I hope you are right, cause my core i7 system will be very expensive as it is :)

Well thanks for your help anyhow and happy new year!

ACook
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Post by ACook » Thu Jan 01, 2009 6:38 pm

According to that calculator, my system would draw 440W at full load.

in reality if it breaks 150 it must be making coffee as well

fyi, I have a 380W seasonic in the system...


(I'll fix my sig later, but that drew similar numbers)

Immersion
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Post by Immersion » Thu Jan 01, 2009 6:41 pm

ACook wrote:According to that calculator, my system would draw 440W at full load.

in reality if it breaks 150 it must be making coffee as well

fyi, I have a 380W seasonic in the system...
That is strange, how it can calculate such wrong numbers...
What does it really calculate is the question :)

FuturePastNow
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Post by FuturePastNow » Sat Jan 17, 2009 4:47 pm

Yeah, that calculator says my system should use over 500W, when in reality it is ~300W max, including two LCD monitors- a 24" and a 19". Those monitors are at least 100W on their own.

Joe Public
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Post by Joe Public » Mon Jan 19, 2009 3:03 am

Immersion wrote:
ACook wrote:According to that calculator, my system would draw 440W at full load.

in reality if it breaks 150 it must be making coffee as well

fyi, I have a 380W seasonic in the system...
That is strange, how it can calculate such wrong numbers...
What does it really calculate is the question :)
Just make sure you select "single socket" when you choose CPU, because if not, it will assume you have more than one CPU and calculate power for several quad core CPUs.

Mine came out as 175W, which is somewhat close to about right. I measure 200W from the wall while gaming. (E6600 @ stock, 2GB RAM, 8800GTS 640MB, one hdd, one optical + the basics)

BillyBuerger
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Post by BillyBuerger » Mon Jan 19, 2009 7:01 am

Immersion wrote:That is strange, how it can calculate such wrong numbers...
What does it really calculate is the question :)
I just ran a system like you mentioned through that calculator...

Core i7 940
3 sticks DDR3
ATI HD4850
1 SATA hard drive
1 DVD +- drive
3 120mm fans
everything else at default

Came out to 307W. I added an overclock to the CPU to 3.5GHz with no voltage increase. (Don't think it's needed is it?) and it only bumped it up to 315W. What else did you put in there to get it up to 509W?

Also note that it adds 26 watts for the DVD drive. That's because they take the maximum that each component could possibly use. Unless you're going to be writting DVDs while gaming, you can easily take 20W off from that. Same thing if you add additionaly PCI devices such as TV turners and such. It's not practical if even possible to max out every device in your PC at once. But this is generally what these PSU calculators assume. Last, it states that it's the recommended PSU wattage, not that actual used wattage. So as you configured it, it was recommending a 509W PSU, not that it would really actually use 509W.

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