How Many Watts?

As the title says this is a question as to how many watts will my new system run. These specs aren't final but it is the sort of specs I want for the price:

Asrock 990FX extreme 3 Motherboard

AMD FX-8320

MSI Twin Frozr GTX 770 in SLI

Crucial Dominator GT 8GB 1866 RAM

Coolermaster Hyper 212 EVO.

What power supply would you reccommend for me, I had a look at a Corsair HX850 PSU for £120. Should I buy this or can I get any cheaper power supplies that can handle this system. Bear in mind that there will be some light to medium OC on the CPU and GPU. 

Hopefully you can come up with a answer...

750W is easily enough for all that. If you get a good power supply, you could do it with less. That includes overclocking and extra drives.

I do recommend the HX750 as a safe bet, and a slightly cheaper alternative to the 850 you are considering.

I've seen an AX760 priced around the same on Dabs (UK). Corsair supplies are highly recommended.

I dont recommend the Asrock 990FX extreme 3 for overclocking i am useing one as a temporary mobo (2 asus mobo's i had where fulty) it has a 4+1 vrm and the mobo is thin it overheats at stock with my FX8320.

As for the psu 850w is more than enuff power 

Under torture test the 8320 will take about 200W

average gaming on the 770s will be abour 400W together closer to 500W on a torture test.,3519-25.html

Knowing that the rest of your system will take around 100Ws(fans and all) probably I'd say an HX850 is enough if you're not OC'ing to the extreme, as it is exponential not linear.

Look into a gold/platnium rated 850W

for a single card setup 500w is more than enough. if you pick a good quality psu. 80+ bronze minimum.

you can run 2 770s off a 650w psu but i prefer to have a little headroom so would go 750w for sli

in general though on a single card build with a slight overclock your probably looking at 380w-420w total 


 140w for the cpu (oc'd)

10-20w motherboard depending on oc 

200w gpu max

rest of the system 40w

Those benchmarks show total sistem power useage the FX8320 is a 125wTDP cpu and the cpu will stay around that tdp at stock at full chat.

Overclocking it however can push it up to 200w (depending how far you clock it up to)

Thanks for pointing out the Total. I did not notice that. I take what i said back.

But still, TDP is not power draw. It's the thermal heat output in Watts

That is true TDP added by the manufacturer is usealy the thermal cut out point in which a cpu will start to throttle its self under normal conditions to operate with in its limitations ie running at stock before overclocking.

You can drastically change the TDP by adding better cooling and overclocking pushing up the power it uses.

I definitely dont reccommend overclocking on that extreme 3 mobo it just isent beefy enuff for even a small overclock on a power hungery 8 core 


thanks for all the suggestions i think I will look into the corsair hx750 thanks again for your help.