Need help choosing a PSU

[biliousfrog]

750w should be ok, look for a decent single rail PSU...don't skimp, it's one of the most important parts of the system.


Corsair/Seasonic or PC Power & Cooling (OCZ) seem to be the standard recommendations.

[hoffman4]

Would I need one that high? On the nVidia website it only calls for a 350w. I plan on overclocking the CPU so do you think I'd be ok with a 650w or 700w?

[olson]

Would I need one that high? On the nVidia website it only calls for a 350w. I plan on overclocking the CPU so do you think I'd be ok with a 650w or 700w?

You'd be fine with 500 watts. :thumbsup:

[meleseDESIGN]

Would I need one that high? On the nVidia website it only calls for a 350w. I plan on overclocking the CPU so do you think I'd be ok with a 650w or 700w?

Actually you don´t need a PSU that high for your confuígurations.
You would be fine with 500W or even a good 450W should be ok.
In my mainworkstation I have a AC Fusion 550W ECO80 PSU and it will support even DUAL CPU Setup.

The system Specs for your references:

Asus Z8NA-D6 Dual Socket 1366 Board
2x Xeon X5570 (each 95W TDP) processors
GeForce GTX260 216SP PCI-E 2.0 graphics card
48gigs DDR3 1333MHz ECC Registered (6x 8GB module) RAM
2x 2TB HDD + 1,5TB extern
6x Fans
2x Asus DVD-RW DL9 drives
Arctic Cooling Fusion 550W ECO80 Silentium Edition PSU

[gawl126]

750w should be ok, look for a decent single rail PSU...don't skimp, it's one of the most important parts of the system.


Corsair/Seasonic or PC Power & Cooling (OCZ) seem to be the standard recommendations.

I agree with these suggestions.

If you're still not sure how much power you should have, use Thermaltake's power supply calculator for a good estimate. I found it pretty useful: http://www.thermaltake.outervision.com/

[olson]

I agree with these suggestions.

If you're still not sure how much power you should have, use Thermaltake's power supply calculator for a good estimate. I found it pretty useful: http://www.thermaltake.outervision.com/

A whopping 327 watts assuming there are 3 120mm fans and a bunch of USB devices. There's simply no need for a 750W power supply. A decent 500W is more than plenty for that configuration. I'd suggest Corsair or PC Power & Cooling. Cheers!

[biliousfrog]

Although I agree that 750w is a lot and more than necessary for this build I went for that purely because it leaves a lot of headroom with regards to overclocking, adding extra HD's, running a more powerful graphics card (which are becoming monsters)....they tend to last a very long time so should be adequate for several years (providing that it's a good one)....and running electronic components at minimal load is better than running them at high load, so a 750w should run happier for longer than a 500w.

Having used Dell's in the past and not being able to upgrade anything because of the PSU I always go for something with plenty of headroom...and they don't cost much more for an extra 100w or so.

[meleseDESIGN]

Although I agree that 750w is a lot and more than necessary for this build I went for that purely because it leaves a lot of headroom with regards to overclocking, adding extra HD's, running a more powerful graphics card (which are becoming monsters)....

There will be enough headroom for OC, running extra HD´s and a more powerfull graphics card even with a good 500W PSU and it also will last a couple years. The only reason when you need 750W and more is when you like to have a SLI/Crossfire configurations.

Look at my specs above for references.
Even a Dual Socket configuration with 3 HDD´s, a GTX260 and 48gigs of RAM work fine with only a nice 550W PSU and this configuration last a little wile.

Maybe PSU´s becomes also more inovative in the future and maybe you will buy a new one anyways in 1 year. I buy allways what i need right now, because technically changes happen so fast nowadays, also for PSU.

[PanzerMKZ]

I would recommend the seasonic or the PC P&C. I have a server with the specs melese is talking about. I run a 650watt in it. Just look for the 80plus label also. Problem with alot of the crap PSU's is they are rated at some stupidly low temp. Yea it might be 750w when it is running in the freezer. But what about the temp at a normal room temp.



Panzer

[jibbaJabba]

Some good advice here.
Yup, be sure to get a good branded one - you really get what you pay for with PSU's. As mentioned - get a high efficency (80%) and you shouldn't have any problems. Also, 700w is overkill for your system but aswell as future proofing (again as mentioned) it will only ever use what it needs so you won't be dimming all the lights in your street whilst your playing solitaire...;)

[eaclou]

Another thing to remember, if it is important to you, is that most PSU's run at maximum efficiency between 20% and 50% of their rated load.

So if your computer is going to be drawing 300W, a 750W PSU will be more efficient than an equivalent 500W PSU. You can do a google search for 80plus, they have a website with efficiency curves of a whole bunch of PSU's so you can check which will be a good fit for you.

Also remember that a PSU's max load is based not only on its rating, but also on its operating temperature (someone above mentioned this) and its age.

Those are the reasons people recommend a lot of headroom.

Anyway, i'd suggest one with a single 12V rail; Corsair and PC Power & Cooling are generally considered the highest quality manufacturers.

[olson]

Another thing to remember, if it is important to you, is that most PSU's run at maximum efficiency between 20% and 50% of their rated load.

Actually its the opposite of that. Power supplies are most efficient with loads greater than 50% of their capacity (but less than the maximum). In this situation with a approximately 350W load, a 450W or 500W power supply. Though to get a more accurate load estimate you'd have to calculate the load for each rail, but generally speaking its close. Cheers!

[eaclou]

check these out as examples:

http://www.80plus.org/manu/psu/psu_reports/Antec_EA-500_500W_80PLUS_Report.pdf
http://www.80plus.org/manu/psu/psu_reports/CORSAIR_CMPSU-750HX_ECOS%201463_750W_Report.pdf

pretty much every PSU follows a similarly trending efficiency curve relative to its rated power.

So the 20% figure was a little low, but 40-50, or 30-60 is where you want to be. Definately not up at 80% though

[olson]

check these out as examples:

http://www.80plus.org/manu/psu/psu_reports/Antec_EA-500_500W_80PLUS_Report.pdf
http://www.80plus.org/manu/psu/psu_reports/CORSAIR_CMPSU-750HX_ECOS%201463_750W_Report.pdf

pretty much every PSU follows a similarly trending efficiency curve relative to its rated power.

So the 20% figure was a little low, but 40-50, or 30-60 is where you want to be. Definately not up at 80% though

Good point, 50% seems to be the sweet spot. Though a lot also look like this where they are more efficient at loads greater than 50% compared to less than 50%.

http://www.80plus.org/manu/psu/psu_reports/SP85-SUPERMICRO-PWS-865-PQ-865W-Report.pdf
http://www.80plus.org/manu/psu/psu_reports/ENERMAX_EG1100%20PRE-PODUCTION_ECOS%201282_1100W_Report.pdf

I guess it comes down to the specific power supply. Cheers!

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