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Minimum psu

Last response: in Graphics & Displays
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August 15, 2012 9:15:05 PM

i'm gonna buy a hd6850 and i was wondering what is the minimum psu wattage that will hold my system..or if i need to change the current one...
i was thinking Sirtec - High Power Element PLUS 500W or Corsair Builder CX600 600W v2 which one would be better ?

CPU: AMD Phenom II X4 Black Edition 955
Mobo: Gigabyte GA-MA785GT-UD3H
RAM: Corsair Vengeance 8GB DDR3 1600MHz CL9 Dual Channel Kit
HDD: Samsung 500GB SATA-II 7200 rpm 16MB SpinPoint F3
PSU: Corsair CMPSU-400CX
no dedicated gpu :p  using the integrated one....

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a b U Graphics card
August 15, 2012 9:19:47 PM

500w will be fine for you, but I can't recommend the sirtec psu because I can find zero information about it online. Obscure does not equal good in the Computing world.
a c 175 U Graphics card
August 15, 2012 9:34:43 PM

Corsair Builder CX600 600W v2
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August 15, 2012 9:46:22 PM

refillable said:
Corsair Builder CX600 600W v2


Second that.
a c 291 U Graphics card
August 15, 2012 9:48:33 PM

Corsair is a much better one!
August 15, 2012 9:58:25 PM

kevin83 said:
500w will be fine for you, but I can't recommend the sirtec psu because I can find zero information about it online. Obscure does not equal good in the Computing world.
Silverstone Strider Essential =Sirtec PC Power & Cooling Silencer MK II = Sirtec they make decent PSU ;) 


a b U Graphics card
August 15, 2012 10:12:04 PM

bogdyy13 said:
i'm gonna buy a hd6850 and i was wondering what is the minimum psu wattage that will hold my system..or if i need to change the current one...
i was thinking Sirtec - High Power Element PLUS 500W or Corsair Builder CX600 600W v2 which one would be better ?

CPU: AMD Phenom II X4 Black Edition 955
Mobo: Gigabyte GA-MA785GT-UD3H
RAM: Corsair Vengeance 8GB DDR3 1600MHz CL9 Dual Channel Kit
HDD: Samsung 500GB SATA-II 7200 rpm 16MB SpinPoint F3
PSU: Corsair CMPSU-400CX
no dedicated gpu :p  using the integrated one....


Since you haven't bought a new PSU yet:

I'm guessing you haven't tried it on the Corsair 400CX yet either. Try that first before you buy a PSU. That Corsair 400CX has a very strong 12V rail, more than the replacement from Corsair rated at 430 Watts.

I used that same PSU in a very similar system to yours (Phenom II, 785 chipset, 2 HDD's) with a HD2900XT before for a few months until I retired the HD2900XT (a much more power hungry card than the 6850). I think you might find that the PSU you have now can power the system you have + the 6850 you are about to buy.

If that turns out for some reason to not be true, you can always buy a PSU then.

EDIT: The TDP of the 6850 is 127 Watts, FYI.
August 15, 2012 10:22:39 PM

thx i will try it first on the 400CX and see what happens... thx to all :D 
August 15, 2012 10:52:33 PM

bogdyy13 said:
thx i will try it first on the 400CX and see what happens... thx to all :D 


I wouldn't advice that, why not just buy the CX500/600? Then you can get a dedicated GPU and there will be headroom for it.
a b U Graphics card
August 16, 2012 12:58:09 AM

bogdyy13 said:
thx i will try it first on the 400CX and see what happens... thx to all :D 


Guru 3D, Anandtech, HardwareCanucks, LegitReviews, etc... reviewed both the 6870 and 6850, and found in all cases with system idle power from about 100 watts to 170 watts, the max load power was only on average about 270 watts as measured from the wall (not even the PSU, it means the PSU is actually delivering less than this, by about 20% for 80% efficient PSUs). This means that a 500 watt PSU is only about maximally half loaded with such a setup under GPU stress, and their setups are more power hungry LGA1366 setups with HardwareCanucks's test config OC'd.

A ROUGH calculation based on published TDPs for worst case gives you:

125W (CPU)x 1.20 (Motherboard and VRM losses, very generous estimate) + 127W (GPU, net) +20W (HDD+SSD+Optical) + 20W (USB 2.0 maxed out for 4 ports) = 310.75 Watts at the PSU.

That 400CX as reviewed at HardwareSecrets (top notch site for PSU reviews) is capable of delivering a whopping 483.9Watts of power, about 120.6% of its rated capacity. See:

http://www.hardwaresecrets.com/article/Corsair-CX400W-P...

I'd say you are at LEAST safe to try, with good reasons to expect it to work fully without any issues and some headroom to spare.
!