How Much Wattage?

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mdale13

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Mar 5, 2009
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I am just about ready to pull the trigger on building a new PC, and have settled on vitually every part except the PSU.
My components:
Intel i7 920 (OC to 3.6-3.8ish)
Corsair H50
OCZ Gold DDR3 6GB (12GB eventually)
EVGA 275 (maybe a 260 SC) either card will eventually be matched for SLI
WD 640GB Black (eventually will had a few 1TB storage drives)
A DVD burner
6-10 case fans

is a 1000w overkill? i would like the PSU to last me as long as possible, 4-5 years of upgrades at least. i was set on an antec 850w, but now i am unsure. any suggestions or insights would be greatly appreciated.
 
Using the monitoring utility software that came with my CyberPower UPS, I was able to monitor how many watts my system was using. First, here's a general breakdown of my system:

- i7 920 on an ASUS P6T, OC'd to 3.8GHz
- 12 Gigs DDR3 memory OC'd to 1523MHz
- 2 X EN9800GT Graphics cards (2x 512MB DDR3)
- 7 X SATA Drives (WD Caviar Black 500GB) in RAID 1 and RAID5
- Coolermaster Cosmos 1000 Case
- Coolermaster V8 Cooler
- 2 Burners

I monitored the power load while playing Call of Duty 5 (World at War), with the graphics settings max out. Based on my test, my peak consumption was 505 watts.

Idle consumption (as I type this post) is 328 watts

My PSU is the Corsair TX750w. So far it's holding up quite well.

Have fun building your new system.

----

Update:

I also stressed my system with prime and ran Call of Duty 5 at the same time. Power consumption went up to 530watts. My PSU was able to handle it, but my UPS couldn't take it anymore. I have the Cyberpower 800AVR, and the specs say it's designed to handle up to 450watts. Looks like I need a bigger UPS.
 
Update:

Looks like the TX750w wasn't holding up as well as I had expected. It turns out the recent crashes I was experiencing was due to not enough juice getting to the system. After using the power calculator on Asus' website, it estimated I needed 1100W. I installed the Thermaltake Toughpower CableManagement 1200W PSU.

Anyway, the point of this comment is if you plan on expanding heavily on your system, like I have, then you may want to get the PSU that will be able to easily meet your requirements.
 
I seriously doubt that your issues were because the TX750 couldn't take it. That PSU could easily (and I do mean easily) supply and OC i7 and a pair of 9800GTs. If it was a PSU issue, it was a single bad unit, because you should not have drawn anywhere near 750 watts on that system. Most PSU calculators recommend >1200W for me, and I'm running just fine on a Corsair HX1000.

What kinds of crashes were you getting?
 
The following behavior started happening after the second graphics card was installed, with the graphics settings set to maximum.

The system would freeze up during game play. About 10 seconds after starting the game the screens would go black, as if the graphics cards were cutting out. Sometimes, the game would resume after 5 seconds, but consistently after a few minutes the system would eventually crash. It was this "cutting out" behavior that made me think it was a potential power issue.

Sometimes I'd get a BSOD on boot up, just as everything was initializing and other times I'd get random memory dumps.

Factor in other devices, like the 12GB of memory, 7 SATA drives, a few USB devices, and 4 Sythe UltraKAZE fans running at 3000RPMs, overclocked memory and CPU, the power requirements starts to add up.

Mind you, in my previous post I mentioned my UPS indicated I was drawing over 500W, however, it was only designed to handle 450W, so I probably wasn't getting a true reading of how much I was actually using.

There's other factors that probably come in to play in addition to wattage, such as regulation of voltage and current delivery. I'm not an expert in this area though, so if there are anyone with an electrical engineering background that would like to add to this please do. Some of the features described on my new PSU include:

-Strict Voltage Regulation provides steady voltage for system
-Independent Voltage Circuit: offers unflappable current delivery under heavy load

That being said, what I do know for sure is that after I installed the new power supply I haven't experienced a single crash, and the behavior I described with the graphics cards has ceased completely.

One last thing. The manual for my motherboard (ASUS P6T) states if you plan to run 2 or more high end graphics cards, you should use a PSU of 1000W or greater to ensure system stability.





 




lol what beast are you running? :), i have a ocz 700W game extreme that is handling stuff written below
6 x delta ultra speed fans
1 x gtx 285 overclocked
1 x q9550 @ 3.84 ghz
2 x yateloon 120mm fan
1 x nidec ultra 60mm fan
4gb ram @ 1000mhz ddr2
4 x hdd
1 x dvd rw
2 x fan controllers
1 x danger den d5 pump
creative audigy sound card (running from mb lol)...

1200w is wow.
 
i believe it might not be your powersupply at all, it is probably your house wiring or phase. I have seen where people have only 1 electrical phase running in their house they end with problems like yours. lol i just graduated in BSEE (electrical engineering) thats why i think it might be a phase problem. You know getting all 750w out of that wall from your pc is pretty hard, also remember when your pc starts up, some things like the fans mostly need a start up voltage which is usually higher then their regular running voltage. but these days most of the components start at a powersaving state when a pc is turned on. All the video cards, processors, and even harddrives do this low state startup. Also what other appliances do you run in your house? is it possible you have an unstable powersupply that cant keep up, also remember if your power supply is rated for 750 watts @ some temp, it will give you those 750w at the specified temps. Power supplies behave like amplifiers once they are out of their comfort zones (temps, loads etc) they dont act linearly and perform much worse then you might expect. I still believe it is your phase problem or a faulty p supply.
 
hey there, i have seen these jeantech psu's on ebay, going at an introductory offer of 70 http://cgi.ebay.co.uk/reward-psu-Jeantech-1000W-Modular-ATX-PC-Power-supply_W0QQitemZ270442038516QQcmdZViewItemQQptZUK_Computing_PowerSupplies_EH?hash=item3ef79a04f4&_trksid=p3286.c0.m14 item number 270442038516 if the link doesnt work, they are 1000 watt modular psu's and are supposed to retail at 130, i have no experience with jeantech but after reading about this particular psu it sounds like a deal to good to pass up, i was considering getting one if my antec 550 wasnt enough to run my new 4890 but luckily it doesnt even struggle with it, hope this helps and if you do go with this choice please let me know how good it is, as if it is as good as i think it is i will go for one anyway :) just so when i go xfire i am ready
 
The answer to your original question is yes. A 1,000 watt power supply is overkill. A high quality 750 watt psu can easily handle your system even with two video cards operating in dual mode.

Corsair, PC Power & Cooling, and Seasonic offer high quality 750 watt power supplies.
 
cjl, Freezed1,

yes, it is possible I was dealing with a bad PSU with the 750, or at least one that didn't handle well under heavy load. Perhaps a higher quality 750 would have met my needs, one that provides better voltage regulation than the Corsair tx750w. In regards to your other questions Freezed1 (cool, I knew we'd get an electrical engineer response), as far as I know, everything else electrical wise in the house is fine. In fact, I'll know for sure next week because we have an electrician coming out next week to do an inspection (house is being sold). As for temps, the computer sits in an air conditioned basement. I'll post back after I hear from the electrician, and when I hook up a new UPS. Hopefully, it will be able to give me some accurate readings on power load.
 

With PSUs you normally get what you pay for. A good quality 1000W modular PSU would be over 200, and would certainly have more than 4 PCIe connectors. 1000W is also overkill for only 2 video cards.

Get a Corsair HX750 instead.
 
So I stand corrected. I must have been dealing with a bad power supply with my last unit. I upgraded my UPS to the APC (865watts), and based on the readings on the LCD display, I haven't gone about 450Watts! Even after hammering the system with Prime95 while playing COD WOW full res, it never went near the numbers I thought I was at before.

That being said, I agree with cjl, a 750PSU is more than enough. (WTH am I going to do with this 1200? :)

 
WOW! This is an interesting thread. Results are pretty much consistent with power consumption charts in articles right here at Tom's Hardware as well as AnandTech and Xbit Laboratories. Very Cool! The general rules of thumb are still applicable.
 

Honestly, as 750W PSUs go, it doesn't get a whole lot better than a Corsair 750. Corsair PSUs have excellent voltage regulation, low ripple, and plenty of excess power capability. If you had a bad one, it was not representative of Corsair PSUs in general.
 
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