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Chosing right Wattage for built.

Hey everybody,

I'm trying to figure out whether I can use my old Power supply( 1 year- 550W)
for my new built. I tried already to calculate the Power needed but I ended up with 335 W. I think that is way to less.
I jope nothing is missing

Here my built:

CoolerMaster 690 II Advanced
Intel Core i5 2500K
2048MB Sapphire Radeon HD 7850
8GB G.Skill Ripjaws DDR3-1600
Noctua NH-D14 AMD and Intel
1000GB Western Digital Caviar Green WD10EARS 64MB 3.5"
ASRock Z77 Extreme4 Intel Z77 So.1155
60GB OCZ Agility III 2.5"
LG Electronics GT60N Slim DVD+-R/RW

If you have any improvements for this built you are also welcome to post them ;)

Would be great if somebody can figure that out or help me to find my mistake.

Thanks everybody
10 answers Last reply Best Answer
More about chosing wattage built
  1. AMD specifies a 500w minimum PSU for a single HD 7850. What is the brand of that power supply?

    Can I also point you to this helpful site?: http://extreme.outervision.com/psucalculatorlite.jsp
  2. What is the make/model of your PSU? Can you use the DVD-R from your old PC? Are you re-using the old case? Does your 335W calculation include OCing? If not, then that number actually looks a bit high for a single 7850 system; actual power usage is likely to be closer 275-300W at full load.

    A system with a single HD 7850 requires a 500W PSU with at least 30A on the 12V rails and one 75W 6-pin PCIe power connectors. Bottom line, a good quality 550W PSU is more than sufficient to power your system and moderate OCs to the GPU and CPU.
  3. Even if you could manage to overclock to 5Ghz your 2500K wouldn't draw as much power as this overclocked I7-965
    http://www.guru3d.com/article/msi-radeon-hd-7850-power-edition-oc-review/6
    254 watts from the wall when running a gamelike application, with a factory overclocked 7850
    With a good quality 550 watt psu you could overclock till the thing is ready to let loose it's magic blue smoke and not have to worry about power
  4. hey thank you all for that answers!!

    I have a Bequiet PSU at home. I bought it 02/2011. Do guys want to have the exact name?

    No I won't re-use my case and DVD-R from my old PC. The DVD-R has an IDE port. The case is too unorganized and old ;)

    I get for the DVD-R the (LG Electronics GT60N Slim DVD+-R/RW)
    and for the case (CoolerMaster 690 II Advanced).

    No the calculation of 335W did not include the OC-ing, because I don't now the wattage of a 7850 or 2500k when it is overclocked.
    I won't buy anything overclocked. But I plan to oc the 7850 and 2500K later on...

    Thanks for all your support!
  5. Bequiet does have some good PSUs. They have about 4-5 550W models; what is the model number of yours?
  6. Rugger said:
    Bequiet does have some good PSUs. They have about 4-5 550W models; what is the model number of yours?


    Cause I am not home right now I try to get my brother to give me the information...
    I hope I will get them tomorrow!
  7. yeahh finally i got the information
    here is the power supply
    http://www.mindfactory.de/product_info.php/info/p661461_550W-be-quiet--System-Power-BQT-S6-80--BULK.html
    550W be quiet! System Power BQT S6 80+ BULK

    Thanks for your help
  8. Best answer
    It is a decent PSU and more than sufficient for your planned build. The 7850 is not a power-hungry part; a system with a single 7850 requires a 500W PSU with a total of 28A on the 12V rails and one 75W 6-pin PCIe power connector.
  9. Best answer selected by Exterminans.
  10. This topic has been closed by Mousemonkey
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