Is a 450 watt psu sufficient for a 7950?

[SeanArce]

Is it?

[zackclark70]

i have 3 7950s on a 750w puling 720w from the wall as long as your 450w psu is a good brand it will be fine 

[Garfield]

No, unless it is a good brand such as a Seasonic or Corsair, or something of a similar build..  I fried a 500 Watt PS that was a cheap one, I forget the brand, and all I had was a Gigabyte 7950.
It worked fine while I mined for 1 month, then just burned out.  no OC or anything.


(Someone posted while I was typing this, but in essence, +1 for the answer.)

[SeanArce]

that's ok then, I ordered a 600w. Now to learn how to install it

[zackclark70]

very simple if the old one is already plugged in just swap the connectors over like for like 

[polrpaul]

Should be fine - give it a go.

[Trillium]

I'm going to say no. Even it works at first, PSU's DC output maximum drops over time. This is because of component aging. Some say this can be up to 20% within the first year and can get even worse over time. This would take your maximum stable output down to 360 watts or less. Of course it depends a lot on the PSU circuit design and component quality, which comes down to the who manufactured the PSU and how much you wanted to pay for it...

It probably wont hurt to try it but if it works at first but then you find instability starting to occur in the future then look very suspiciously at the PSU.

Monitor the voltages of the PSU with a program from your motherboard vendor or use something like System Information for Windows (SIW) which is a great little program for monitoring all kinds of stuff. If you see substantial changes (a few percent) in any voltage reading then you are most likely overloading the PSU or it is just a piece of junk to begin with. My 1000 watt Corsair PSU is 5 years old and delivers rock solid voltages that never fluctuate more than +/- 0.01 volt even when I start mining on 500 watts of GPUs.

Because you don't give any information whatsoever about the brand or model of the PSU you have, I might suspect that it is something like a generic PSU that came with a case you purchased. There are countless generic companies manufacturing PSUs in Asia and I would not trust them at all. Usually these generic PSU not only have terrible components that are unlikely to last (especially under load when mining...) but they also can be terribly inefficient meaning your power bills will be larger than if you had a quality PSU with a meaningful efficiency certification eg 80+ silver/gold/platinum or better. Can you have a look on the PSU and let us know who the manufacturer is and if there is a product code associated with it?

[fractalbc]

The question you asked

Is a 450 watt psu sufficient for a 7950?

The answer is YES, with ease, as long as it is a single rail supply.

The question you SHOULD have asked

Is a 450 watt psu sufficient for my system with a 7950?

The answer is "dunno, what else is in the system".

A mining rig with a low power processor, a few gig of ram and a single low power drive?  Easily and with room to spare.

A spare parts rig with an old prescot era p4 with an old ide drive and a bunch of fans?  Maybe, but I wouldn't count on it.

A gaming rig with an i7 or x6 with 16 gig of ram, 4 or 5 hard drives and glow lights?  Not a chance.

[tstang]

Hi,

Basically the Rule of Thumb for 7950 is 200W to 250W per card.

Your MB and system will take up about 50W to 100W.

If you use good quality PSU, like Corsair or Seasonic, then 450W would be more than enough.

Please remember that like Corsair Gold 450W promise 450W to your system. AT 80% efficiency and 100 load, the power it will draw 560W at the outlet.


IF you are using Windows system, you can use MSI Afterburner to lower down the Voltage which will reduce the power consumption by 30W to 60W per card depending on your setting.

I'm running TWO 7950 from Corsair 450W only.

Hope this help.

[malevolent]

Some misinformation is in this thread..
I ran 3x OC'd (to 900MHz, no voltage increase, later underclocked my memory to <300MHz) HD 5850s 2 years ago on a 550W Corsair PSU without problems, I only had to decrease the overclock of my Q9300 (3GHz instead of 3.5 GHz so that it could run on standard Vcore and pull less power).

A high quality PSU can run @ 100% load (or even slightly beyond that) 24/7/365.

A decent 450W PSU is enough for a rig with a 7950, a quad core CPU, 16 GB of RAM and 4-5 HDDs.
The RAM itself draws very little power, about 2-3 watts per stick, HDDs - about 10 watts each.

At 90% load a good PSU will still be very efficient, especially if one is using 220-240VAC instead of 90-120VAC.

If it's a cheap one, even 1kW may be too little for a mid-range GPU system (don't trust everything a no-name PSU sticker says).

As for measuring the voltages of the PSU I wouldn't rely on the cheap inbuilt sensors - use your own quality multimeter to measure the +12VDC rail(s).

[notlist3d]

All depends on what else is running in your system.  I would say normal 380ish watts (used kill-a-watt) on cards seeing with mining.   Varied by card was interesting.  I had a 730 power supply was not able to do 2 cards and system.  But a 850 covered easily.  So a lot depends on system, and also brand of PSU not all are equal.