Psu maths

red eye

red eye

red eye

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Over the hills and.......
How do I work out how much wattage I need? I know the volts my 2500k is using but what sofware to use to read amps used by my cpu and gpus? I know there are online calculators but that recommended a 800 watt, but while it let me oc my cpu there was no such option for the gpus and I would rather do the math myself

I'm trying to oc my two r9 290. I can get 1110 stable in heaven but when playing crysis 2 it black screens I'm using a 850watt seasonic x.
 
and how do u know its the psu ? if it psu i believe it would just shut down the pc.

its the same for me. i can do 1150 oc on cores in benchmarks, but when playing crysis i have to go with 1060 otherwise it locks.
Every 3d application is different. some may work with 1100 clock, some with 1050.
 
I don't know its the psu I just want to rule out the psu and also because I'm curious to know how to work it out.

I have tried crysis 2 with 1050/1400 and also 1050/1300 and it black screens, though it runs fine at 1000/1300.
 
Looking at some reviews, stock crossfire 290's come in around 700-750w total system power. Your Seasonic is a very good psu with a single 12v rail of 840w so it should be enough but maybe the overclocking is just pushing it over the edge. It could also be a unstable overclock though.
 
This crossfire thing is getting annoying. Last week I unplugged gpu 1 (msi) and benched gpu2 (shapphire tri x) got it up to 1170/1300, so today I had a go on crysis 3 and it worked fine. bumped the core up to 1200 and it black screened, now the screen flickers on desk top then black screens.

Thought it was after burner applying 1200/1300 at start up so deleted that in safe mode still flickers. connected the msi back up and now flicker free. Just benching haven at the shapphire stock and scored 2308 91fps, which is up from 74.4 fps 1873.
 
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