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Sapphire 6870 Doesn't Boot with Computer

Last response: in Graphics & Displays
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Hi Everyone,

I built a computer a while back and about 4 months ago I upgraded from a sapphire hd 4870 to a 6870. At the time that I did this, I had no problems getting it to boot. I then drove it across state lines, set it back up and it didn't work. My first consideration was that the motherboard or graphics card had been damaged in transit, but after RMA'ing the card, and testing the one slot on my motherboard with a second card (GTX 285) I found that it worked just fine. I got the card back from Sapphire, and tried it in a friends computer, and it ran just fine. After some more experiments and research I came to the opinion that it might be the PSU.

I tried my card with a friends PSU which is a 500W something-or-another and it worked. I then connected the boot drive, the graphics card, and the motherboard connectors and tried again with my card, and found that it worked as well. Satisfied with this, I put it all back in the case, carefully checking where I plugged each part (although I suppose I could have gotten it wrong) and once it was back and routed, it wasn't working. I unplugged everything except for the boot drive and the graphics card again and still can't get it to work. After plugging the GTX 285 back in, I found that with that card the computer still runs.

Any ideas on whats going wrong? Is it possible I'm drawing too much current off of one rail? If so how do I check such a thing assuming I don't have an ammeter or a voltmeter, or anything but a screwdriver really?

Specs:
Motherboard: Gigabyte EP45-UD3R
Processor: Intel E8500
Graphics: AMD Radeon HD 6870
PSU: Thermaltake Tough-Something 750W w/ 12V 18A Rail
Raided Boot Drive on 2 10k Raptors (Probably a significant power drain, but I'm not really sure)

Thanks for your help

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Hello and welcome,
The GTX 285 draws much power from the PSU the the PSU should be fine.
Link your PSU if possible, this is really a strange problem, you said you took the PSU from your friend and tested it with HD 6870 and it worked ? was that in your rig ?
When you installed the HD 6870 back to your case, did you test it using your PSU or your friends ? or both and you failed to make it boot ?

Also, check that you properly connect 2 x 6 pin PCIE, the HD 6870 doesn't require 8 pin PCIE connector, also try to boot with your GTX 285 and upgrade to the latest BIOS in case you have a compatibility issue with your GPU and MOBO.

This is the PSU:
- https://thermaltakeusa.com/Product.aspx?S=1207&ID=1508#...

The 500 Watt PSU that I tested was plugged into my stuff yes, but I didn't go through the effort of actually mounting it.

I first plugged the 6870 into his rig, which had a different 800 Watt PSU and it booted. Then I plugged the 500 Watt PSU into my rig, and tested it with the GTX 285, which worked as well.

After this I replaced the GTX 285 with the HD 6870, and that worked as well, still using the 500 Watt PSU. Then I switched back to the 750W Thermaltake PSU and it worked as well.

I then had to unplug the PSU Connectors in order to get stuff back into the case. I did some wire routing through the back panel of the case, which involves some sharp turns, but its wiring, so it really shouldn't matter all that much. After I plugged them back in though, the 6870 didn't work anymore. I plugged the GTX 285 back in, and it worked fine.

I used the 2 x 6 pin PCIE plugs each time, and I am pretty sure I'm at the most recent BIOS, but I'll check. It has worked with this version of the BIOS previously though.
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Sorry I should clarify. Even when the 6870 is plugged in with the 750W PSU, the computer boots, but the 6870 doesn't 'activate' for lack of a better word. If I have the speakers plugged in, I can hear the computer start up, and then I can type my password, and open up music files and play them if I don't make typos. The only thing that isn't working is the graphics card.

I am unable to get the HD 6870 to work with the 750W PSU plugged in, but I can get it to work with the 500W PSU plugged in. I haven't tried both, because that seems like a bad idea, and definitely a short term thing if you could somehow get both to supply power.

I've checked the seating on the card a dozen times, as well as all the PSU connectors, just hoping that I was an idiot and didn't plug it in correctly unfortunately.

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zentrix718 said:
Quote:
Sorry I should clarify. Even when the 6870 is plugged in with the 750W PSU, the computer boots, but the 6870 doesn't 'activate' for lack of a better word. If I have the speakers plugged in, I can hear the computer start up, and then I can type my password, and open up music files and play them if I don't make typos. The only thing that isn't working is the graphics card.

If you're able to hear windows environment, it might be a connectivity issue, try using other output such as DVI/HDMI.

Quote:
I am unable to get the HD 6870 to work with the 750W PSU plugged in, but I can get it to work with the 500W PSU plugged in. I haven't tried both, because that seems like a bad idea, and definitely a short term thing if you could somehow get both to supply power.

I won't lie to you, i'm getting confused by the PSUs story, but in short, if you're able to run the GTX 285 with the 750W PSU and the HD 6870 can't be run using the same PSU, the PSU is fine and no problem with it and i checked it, thermaltake is known for it's ToughPower series, but you're current PSUs is not that bad and can handle 2 HD 6870s in CF.
So, again it might be a connectivity issue, if you're able to press the num lock and the KB flashes then everything is working as it should but you have a compatibility issue between your monitor and the GPU.

It worked in this configuration for about a month and a half, and I am pretty sure I didn't make any BIOS changes since it last worked, so I'm hesitant to agree with you that its a compatibility issue, but is it possible I'm using the wrong kind of DVI cable? I'd feel super dumb if I was...

Scratch that last post. It was the wrong kind of DVI Cable. I feel extremely dumb for not checking that. I was thinking about it, and it was the only thing that was different between yesterday afternoon and when I put it all back in the case. Thanks for all your help!
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