Advice choosing a PSU ? Only drawing 550w MAX ??

[bilabonic]

Hi All

I have an MSI Mb and x2 280x cards and it's only using a 550w max . I am not concerned about the efficiency as i have free electric in work 

The biggest factor is price.

Is there a formula or % to add to the 550w being used ??

Or do you subtract a figure from the PSU rating ??

I am also based in the UK

Thanks

[pletharoe]

How did you come to the 550W figure?  According to https://www.asus.com/Graphics_Cards/MATRIXR9280XP3GD5/#specifications each card needs 300W.

Then you also need to factor in the power used by the rest of the machine.

Then add a factor of say 20% to accommodate spikes in power draw.

I'd look at something with 700 - 800 watts and 80plus certification.  Stick to the big brands.  Wattage isn't actually the best measure... taken from http://www.extreme.outervision.com/PSUEngine


The recommended total Power Supply Wattage gives you a general idea on what to look for BUT it is NOT a crucial factor in power supply selection! Total Amperage Available on the +12V Rail(s) is the most important, followed by the +5V amperage and then the +3.3V amperage

[bilabonic]

How did you come to the 550W figure?  According to https://www.asus.com/Graphics_Cards/MATRIXR9280XP3GD5/#specifications each card needs 300W.

Then you also need to factor in the power used by the rest of the machine.

Then add a factor of say 20% to accommodate spikes in power draw.

I'd look at something with 700 - 800 watts and 80plus certification.  Stick to the big brands.  Wattage isn't actually the best measure... taken from http://www.extreme.outervision.com/PSUEngine


The recommended total Power Supply Wattage gives you a general idea on what to look for BUT it is NOT a crucial factor in power supply selection! Total Amperage Available on the +12V Rail(s) is the most important, followed by the +5V amperage and then the +3.3V amperage

Thanks for reply.

I'm using a kill-a-wattmeter, the MAX it has used is 550w inc MB. I just want to run 2 cards off the MB/PSU.

So add 20% to 550w = 660w, so a 700/750w 80plus will be ok.


Think i will get this -

http://www.dabs.com/products/coolermaster-700w-g-series-g700w-80--bronze-power-supply-8Z2S.html?refs=394900000&src=3