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PC wont power on when I plug in 7950

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  • Computers
  • Power
  • Graphics
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Last response: in Graphics & Displays
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January 5, 2013 2:48:42 PM

Ok I got the sapphire 7950 like a few days ago and it worked perfectly and then I went to take a shower a few hours ago and I came back and noticed my computer was off. So i did a bunch of stuff to see what the problem was and I noticed that my computer would boot when I unplugged the 2 PCI connectors. I have a spare computer as well so I tested it with that and the SAME FREAKING problem wont boot with the 2 PCI connectors in. I then plugged in the 6770 I upgraded from and it worked fine. Ive tried googling for a fix but had no luck, maybe someone here can help me. I would hate to RMA the 7950 so soon.

More about : wont power plug 7950

a c 109 U Graphics card
January 5, 2013 2:52:24 PM

PSU ?
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January 5, 2013 2:58:27 PM

its not the PSU, I tried it with 2 different ones, same problem
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a b U Graphics card
January 5, 2013 3:17:23 PM

Yes it could be both PSUs. Like one of them having problems and the other one simply not being powerful enough.

Please give us exact brand and model of both PSUs otherwise we can't help you.
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January 5, 2013 3:23:44 PM

I use this 750w PSU http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I tried the 7950 on my other PSU which is 550w diablotech



I still fail to see how it is my PSU when it worked perfectly fine until now and I went to that site and it recommended 380w max for me. both of my psus fulfil that requirement.

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a b U Graphics card
January 5, 2013 3:43:09 PM

Well, for Diablotec, you have to divide the rated power in half to get real wattage. And the first one is probably kind of wonky also and might have been defective or on its last legs.
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a b U Graphics card
January 5, 2013 3:43:40 PM

elietu said:
I still fail to see how it is my PSU when it worked perfectly fine until now and I went to that site and it recommended 380w max for me. both of my psus fulfil that requirement.


Not necessarily, a lot of bad PSUs won't deliver what they claim.

For instance I made some quick search and Diablotech have terrible reputation, so I highly doubt it will deliver the 500W recommended by AMD for a 7950 (or even that 380W you're asking). Some power supplies can have very bad power fluctuations which could damage the card. It's really not a good idea to get a cheap PSU if you plan to match it with high end hardware like a 7950.

That being said Kingwin reputation looks average, not the best but not the worst. So that 750W should get the job done. However, it could be simply defective and not delivering enough power or have already damaged the card. And the other Diablotech is probably too crappy to run a 7950.

It's hard to tell, it could also be the 7950 that failed or that already had a defect like almost DOA. But if the whole computer shut down it's probably indicating a lack of power. Do you have any friends with a better PSU in which you could test the card in a third system?

If you have money to get a 7950, I would suggest you invest more in your PSU in the future. Get a good brand like Antec, Corsair or Seasonic. For instance, I have a Corsair 650TX v2 (650W) and I know it will deliver what it claims and be more stable, I feel safer than with a 850W "no name" brand.
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a b U Graphics card
January 5, 2013 4:27:38 PM

^@MC_K7 +1.

Cheap no name units can never output power as rated. Most of the time it's half or sometimes it's even lower
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January 5, 2013 4:35:42 PM

MC_K7 said:
Not necessarily, a lot of bad PSUs won't deliver what they claim.

For instance I made some quick search and Diablotech have terrible reputation, so I highly doubt it will deliver the 500W recommended by AMD for a 7950 (or even that 380W you're asking). Some power supplies can have very bad power fluctuations which could damage the card. It's really not a good idea to get a cheap PSU if you plan to match it with high end hardware like a 7950.

That being said Kingwin reputation looks average, not the best but not the worst. So that 750W should get the job done. However, it could be simply defective and not delivering enough power or have already damaged the card. And the other Diablotech is probably too crappy to run a 7950.

It's hard to tell, it could also be the 7950 that failed or that already had a defect like almost DOA. But if the whole computer shut down it's probably indicating a lack of power. Do you have any friends with a better PSU in which you could test the card in a third system?

If you have money to get a 7950, I would suggest you invest more in your PSU in the future. Get a good brand like Antec, Corsair or Seasonic. For instance, I have a Corsair 650TX v2 (650W) and I know it will deliver what it claims and be more stable, I feel safer than with a 850W "no name" brand.


Radeon HD 6770 108 Watts
Radeon HD 7950 200 Watts

The 6770 still works fine on both PSUs, now I know the difference is 92 watts, but the fact that the 7950 was working for a few days on the kingwin no problem and now fails to boot with it or the diablotech makes me think the 7950 has failed...
I know the diablotech is bad but kingwins actually have about the same ratings on sites like newegg compared to certified expensive PSUs....

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a c 109 U Graphics card
January 5, 2013 4:41:50 PM

Yes, the kingwin is a decent psu it will do for any 7950.
RMA the card.
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a b U Graphics card
January 5, 2013 6:09:33 PM

As I said Kingwin reputation is average but not disastrous. The only problem is that your PSU has no Bronze certification so it's hard to tell how much power it can really deliver in a safe way. Next time make sure you get a PSU with at least 80 Plus certification, it will assure you that it delivers 80% of its total power in a stable and sustained way.
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a b U Graphics card
January 5, 2013 6:17:45 PM

MC_K7 said:
As I said Kingwin reputation is average but not disastrous. The only problem is that your PSU has no Bronze certification so it's hard to tell how much power it can really deliver in a safe way. Next time make sure you get a PSU with at least 80 Plus certification, it will assure you that it delivers 80% of its total power in a stable and sustained way.


80 Plus certification has nothing to do with how much power it can deliver in a safe way. It tells you about the minimum percent differences between power drawn by computer components at 20% 50% and 100% of maximum rated output and power drawn from outlet, that is efficiency. The only relevancy is that certified powersupplies tend to have better components and thus safer.
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a b U Graphics card
January 5, 2013 7:10:07 PM

yyk71200 said:
80 Plus certification has nothing to do with how much power it can deliver in a safe way. It tells you about the minimum percent differences between power drawn by computer components at 20% 50% and 100% of maximum rated output and power drawn from outlet, that is efficiency. The only relevancy is that certified powersupplies tend to have better components and thus safer.


than what do you suggest is the best method to choose a good psu?
actually even I thought 80+ certification is the safest way to go
to be humble even I don't know
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a c 291 U Graphics card
January 5, 2013 7:18:21 PM

Looks like the card is shorting the power and PSU protections kick in turning it off. I'd contact card warranty.
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a c 117 U Graphics card
January 5, 2013 7:19:45 PM

yyk71200 said:
80 Plus certification has nothing to do with how much power it can deliver in a safe way. It tells you about the minimum percent differences between power drawn by computer components at 20% 50% and 100% of maximum rated output and power drawn from outlet, that is efficiency. The only relevancy is that certified powersupplies tend to have better components and thus safer.


:o 
why yes it does; it tells you it can deliver 80% of what it is drawing from the wall. actually you said that directly contradicting yourself . . weird.

now if you were to say an 80+ certified PSU doesn't guarantee it will always deliver its labeled wattage . . .
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a c 291 U Graphics card
January 5, 2013 8:10:46 PM

It does guarantee it actually. To get 80+ certification, PSU is tested at 100% labeled wattage.
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a c 117 U Graphics card
January 6, 2013 12:32:46 AM

Sunius said:
It does guarantee it actually. To get 80+ certification, PSU is tested at 100% labeled wattage.

why yes it does , i mistook:
Power Supplies With Fake 80 Plus Badges

so therefore they're not even a 80+ PSU . . . thanks for the correction.
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a b U Graphics card
January 6, 2013 6:23:09 AM

if faking is what people fall prey to....the only thing we can do is tear apart the psu to check if the components are of good quality.
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February 21, 2013 3:43:39 AM

elietu said:
Ok I got the sapphire 7950 like a few days ago and it worked perfectly and then I went to take a shower a few hours ago and I came back and noticed my computer was off. So i did a bunch of stuff to see what the problem was and I noticed that my computer would boot when I unplugged the 2 PCI connectors. I have a spare computer as well so I tested it with that and the SAME FREAKING problem wont boot with the 2 PCI connectors in. I then plugged in the 6770 I upgraded from and it worked fine. Ive tried googling for a fix but had no luck, maybe someone here can help me. I would hate to RMA the 7950 so soon.


I have had the exact same issue, installed a new sapphire 7950 on sunday, today on wednesday it stopped working in the middle of mass effect 1, I had a slight OC on it, but no voltage mod and nothing extreme 1050/1350 if I remember correctly.

further investigation shows that whenever I plug something into the 6-pin power plug closest to the HDMI ports it will instantly fault my power supply. I have a coolermaster 650W power supply which is rock solid and has an LED indicator for faults it says "over-load, short circuit, over-volt" etc. So basically anything put on the 6-pin rail causes my computer not to boot. I can boot using the other 6-pin but of course no video then.

Switched out for 5850 and 4870 both work. I took a multimeter to the pins but I see no obvious short or what not. my engineering instinct tells me that it's an issue with the onboard power reg, causing a huge draw on boot or short.
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February 21, 2013 3:44:02 AM

lemme know if you get a solution, I'm going to try it again tomorrow, then RMA for me.
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June 4, 2013 9:21:41 PM

sorry to dig up an old thread, but did you manage to fix this problem? I just ran into the same thing :/ 
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August 29, 2013 1:31:43 AM

same problem for me... anyone got a solution? i dont know which part is wrong in my pc, the psu or the vga, so i'm not sure which one to RMA
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!