Dual cards, one PSU. Quick Question!

[samuraizero]

I have a 280x and a 7950, running on an ultra bronze 750 watt psu.

When running a single card, it works fine, when I add the second card, computer dies.

750 watts should be plenty for these 2, shouldn't it?

 

[nwo]

750W should be enough if it is a decent quality PSU.

Provide us with a link to the exact PSU model you have.

Your PSU might have split rails and you are trying to run both cards on one of the rails which is overloading it and causing your PC to shut down. Or, it simply doesn't have enough power on the 12v rails because it is a crappy unit and unable to provide 90%+ of its total rated wattage output on the 12v rail(s).

 

[lehtv]

750W should be plenty, yes. I'm afraid Ultra isn't the highest reputation PSU brand... but I'm a bit surprised the crossfire setup simply won't work. It's possible your Ultra unit is simply faulty. What's the exact model number, and is it still within warranty? How old is it?

Just to check- have you tried running it with just the second card but not the first one? That would single out the card as the culprit.

 

[jonnyGURU]

750W should be enough. And while Ultra's quality has been up for question for the last five years, the fact of the matter is if it is rated for 80 Plus Bronze, it is rated to do so at 100% load as much as lower loads.

So you need to define "computer dies" as "shut down", "reboot", etc.

Also, a complete system run down would help, as well as what you're using the PC for. i.e. does the PC "die" when you try to boot up, try to run a game, try to mine for bitcoins, etc.

 

[FalseChristian]

This is why I only buy Cooler Master PSUs. My 750w GXII has been going strong for 4 1/2 years without 1 problem. It was a bit more expensive but there are some computer parts you just can't skimp on (PSUs being 1 of them).

 

[Tristor]

This is why I only buy Cooler Master PSUs. My 750w GXII has been going strong for 4 1/2 years without 1 problem. It was a bit more expensive but there are some computer parts you just can't skimp on (PSUs being 1 of them).

I agree with your sentiment, but lest we lead anyone reading this astray I should point out Cooler Master has had a shaky reputation over the years as well although some of their recent units are pretty decent. Ultimately very few companies actually make their own PSUs, so you need to find out what OEM made the particular make/model of PSU you're considering purchasing and try to find more information out before purchasing. Good places to look for PSU information are TechPowerUp and JonnyGuru. Good OEMs (long track record of quality) are Seasonic and Enermax. For a long time a lot of the Corsair PSUs that were so highly rated were made by Seasonic, a lot of the XFX PSUs are made by Seasonic, some of the older better Antec PSUs were made by Seasonic, some of the BeQuiet Pro series are made by Seasonic, etc.

 

[Bubbleawsome]

It's funny because the only PSUs I've ever used turned out to be seasonic OEM.
I can say they've never failed.

 

[john3850]

I ran a 930 at 4200MHz with a 5970 and a 5870 on a 6 year old orignal 750w PC power and cooling power supply.
Never had any trouble with any single line ps.