Not sure how much power needed


Aug 18, 2011
I have this build lined up for the end of the year but am not sure how much power is needed.

I plan to add another 6950 and more ram in future and may consider overclocking later.

I can spend up to $125 on a PSU, the cheaper the better though

Core = Intel Core i5-2500K 3.3 GHz


HDD = SATA Samsung 3.5" 1TB HDD

DVD = Samsung SATA 22x Black DVD RW

VGA = Powercolor 1GB 6950

RAM = G.Skill Sniper 4G Kit (2Gx2) DDR3 1600

Mobo = Z68 Extreme3 Gen3


Aug 3, 2011
your combination overclocked will probably draw a max around 450-500W. Adding a second 6950 would push to at least 650W. So a 650W might be enough, but it is cutting it close without actually measuring the power draw beforehand. The 750W suggested would be enough. Even if you can't get that exact model, you should be able to find another quality 750W supply, like the Antec Earth EA-750W for AU$121.


Looking through the rubbish PDF list they supply, I would opt for the Corsair TX750 for 143.

Do not Skimp on the PSU, Every single component in the PC relies on it for stable power! A Cheap CPU that does not supply the correct balance over the Rails can BLOW, Taking out your expensive components with it!

Corsair make some of the best PSU units around, I have run my TX 750 with 1055t x6 @ 4.3GHZ and 2 x 5850 @ 950MHZ with Asus Crosshairs IV and several drives and Fans! Easy peasy!

650w will me enough till the second 6950, but honestly a waste to buy 2 supplies!

Here is Power calculator

I calculate 590W as minimun, so 650W is a little close for comfort, 750W for fully configured crossfire and room for a OC you need 750!
-By the end of the year, your parts list will likely change significantly.

-From what you listed, I see no way for you to benefit from Z68.

Launched 5 months after the P67 and H67 chipset the Z68 chipset combines the advantages of the H67 and P67 Chipset so that overclocking, dual dedicated graphics cards and use of the integrated CPU graphics is available. Whilst on the surface it would seem that this would be the chipset to go for, how many users that have 2 dedicated graphics cards will actually want to use the onboard graphics when they already have 2 more powerful graphics cards in their system anyway?

The only real advantage is for users that wish to access the HD graphics features such as quick sync, but considering it’s only supported by very few transcoding programs and there are not many people out there that need or will want to transcode, it makes it almost pointless to choose Z68 over a P67 chipset.

Same applies to users that want to overclock the CPU but use the onboard graphics card; it’s a very limited market.

Finally, another feature of a Z68 chipset is known as SSD caching which is where it allows the use of a small (say 10 or 20 GB) Solid state hard drive to act as a cache for a larger ‘traditional’ hard disk. If you are already planning the use of a Solid State drive this feature is redundant.

If you can’t afford a decent size SSD (40GB+) then there are more cost effective ways around using a small SSD and SSD cashing like spending less on a motherboard, (H67 chipset or even a P67 chipset) and putting the saved money into a decent size SSD.

-What resolution ? At 2560 x 1200, grab the 6950's. AT 1920 x 1200, there's better choices.

Guru3D uses the following games in their test suite, COD-MW, Bad Company 2, Dirt 2, Far Cry 2, Metro 2033, Dawn of Discovery, Crysis Warhead. Total fps (summing fps in each game @ 1920 x 1200) for the various options in parenthesis (single card / SL or CF) are tabulated below along with their cost in dollars per frame single card - CF or SLI:

$ 240.00 6950 (479/751) $ 0.50 - $ 0.64
$ 260.00 6950 Frozr OC (484/759) $ 0.54 - $ 0.69
$ 205.00 560 Ti (455/792) $ 0.45 - $ 0.52
$ 360.00 6970 (526/825) $ 0.68 - $ 0.87
$ 220.00 560 Ti - 900 Mhz (495/862) $ 0.44 - $ 0.51

The 900 MHz 560 is $20 cheaper (here in the US anyway) but outscores the 6950 by 3% ..... no bigga deal .... but when paired in SLI / CF, the 560 really begins to shine with the lead growing to 10%. I checked ya site but it's one of the most user unfriendly sites I have aver visited. Found this one:

Went thru that 1st as PSU much depends on the GFX card choice. I'd suggest the following 750 watters:

XFX Core Edition (9.5 jonnyguru performance rating)
Antec HCP / HCP (9.5 jonnyguru performance rating)
Seasonic X Series (9.5 jonnyguru performance rating)
XFX Black Edition (10.0 jonnyguru performance rating)
Antec CP* / SG series (10.0 jonnyguru performance rating)
Corsair AX / HX Series (10.0 jonnyguru performance rating)

* An 850 watt PSU but generally 1/2 to 2/3 the price than most comparable 1st tier PSU's .... requires compatible Antec case (P183, P193, 1200, DF-85)

A 750 watter will handle twin 6950's or 560 Ti's when both GFX cards and CPU are overclocked.


Aug 18, 2011
Thanks for the advice.

I think i will go with a 750w PSU. Will the Cooler Master GX 750 be ok. I have it priced at $110

I'm getting the Z68 because i have limited range and limited money but would prefer others chipsets. I'm going for that motherboard because its the cheapest CF board there

I have a 1920x1080 monitor and a 1gb 6950 is $209 ATM also there is no 560 ti for some reason but might be in future


Aug 1, 2011
A Quality 600W PSU would be fine. Graphic Card companies usually recommend a lot more powerful PSUs than whats actually necessary. If you've read the latest tomshardware article about PSUs :,2916-11.html

The system with a GTX 580 draws a load power of 488W. I guess 2 HD 6950's won't draw more than 500W. So you'll be fine with Corsair CX600 V2 or Antec Neo Eco 620 or Seasonic X 620.


well according to bit tech a 6950 1gb draws 278w. so 550w for crossfire. and then you will need power for the case gpu hdd and ram... 750w is recommended. corsair tx series is good, ocz zs series, pc power and cooling silencer mkII, antec hcg series, xfx core edition pro series are also all good. that rounds up all the 750w psu's that should be under your budget.