Bad psu for R9 380?

[amadeok]

Hello,
I recenly bought a R9 380, i tried it on a old lag 775 motherboard with a core 2 duo e8500 and a 600w psu with 20a on the 12v rail, but the card acts strangely, rarely ever i can see it reaches past 100w consumption, and gpu z and sapphire trixx record its usage, voltage and amperage going up and down continously during gaming. I tried a stress test with stock clock and the pc completely shuts down every time. I lowered the clocks to 700 and 1100 on shader clock and memory clock respectively and in this way i managed to have a stress test but still after a minut of stable amperge and voltage it starts going up and down fron 10-20 to 100 watts and ampers each. My father used a tool to measure the voltages on the 12v rail and he saw that under the stress test(with lower clocks, 700 and 1100) the voltage went down to 11.40
This means the PSU is not good enough for the task right? Maybe the motherboard and the cpu are also bottlenecking? I saw the both cores on 95-100% usage during gaming.
thanks in advance

 

[TheKliqx]

Yeah, a dual core with that card will cause some serious bottlenecking. As for the PSU 600w should be enough for what you have as my system only has 150w more and I'm running an i7, r9 370 4gb and 5 case fans with still a large amount left.
If you have another newer PC see if you can install the GPU into that and or get a new processor as a dual core will need to be updated anyway.
Try getting a quad core CPU and I am almost certain it will work with a 600w PSU and no PSU upgrade is needed.

 

[amadeok]

Yeah, a dual core with that card will cause some serious bottlenecking. As for the PSU 600w should be enough for what you have as my system only has 150w more and I'm running an i7, r9 370 4gb and 5 case fans with still a large amount left.
If you have another newer PC see if you can install the GPU into that and or get a new processor as a dual core will need to be updated anyway.
Try getting a quad core CPU and I am almost certain it will work with a 600w PSU and no PSU upgrade is needed.

What about the shutdown and the lower voltage in the stress test ? THis an old psu been running for years, maybe its not delivering enough power?

 

[TheKliqx]

Possibly, could be a bunch of things causing the issue but the PSU is the most likely cause.

 

[BerettaOnTheNightStand]

"psu with 20a on the 12v rail"

There's your problem. You either need a 30A-35A on a 12V single rail, or that combined amperage on a multi rail.

Just so you know, to find the combined amps of a multi rail; add each of the rails amps together, then times that number by .725 and voila, your PSU's combined amerage. Just make sure it's continuous amps, and not peak amps. Peak amps are just a marketing ploy and count for nil. And just as a side note; if you're planning on gaming or whatever for longer than 8 hours a day, make sure there is a 5-10 amp buffer. Ex: if an R9 380 needs 33 amps, get a 40 or 45 amp PSU. This is because extended usage causes the amerage to drop 5-10 amps.