Was working, now no output and fan spins full speed (HD5870)

[Ease]

Is my HD5870 dead?

My computer was working completely fine, I shut it down as I normally do before I went away for a couple days, but then when I came home and turned it on it didn't boot up properly.

Nothing appears on screen, the mother board (GA-EP41T-UD3L) LEDs all come on before blinking twice, then after about 15 seconds the fan on the HD 5870 comes on full blast for about a minute, before slowing down to regular speed. Then after another minute the Windows login sound plays, and if I tap Shift 5 times the 'bleep-bleep' of Sticky Keys plays, but still no output to the screen. I should note that normally it starts up in under 30 seconds, rather than the 2 minutes+ it's taking now.

I've tried unplugging all the power cables to the GPU and thoroughly cleaned everything with compressed air. I've also tried all the HDMI and DVI ports with two different screens.

I'd really, really appreciate any and all advice you guys can give me!

<edit>Oh, and my motherboard has no integrated GPU so I can't test if it's definitely the graphics card.</edit>

 

[Purgatory]

What PSU do you have (make and model number), also try resetting the BIOS. To me it sounds like the graphics card is on the way out or the PSU is suddenly not powering it correctly or the PCI-E slot on the motherboard is not working correctly or just the motherboard has gone bad. Shame the motherboard only has one PCI-E x16 slot, I would have said try it in another slot. If you have a spare machine try the graphics card on that to rule it out but make sure the other machine has a good PSU to power it or it may not power up again.

 

[Ease]

The PSU is an OCZ ModXStream 700W. I've reset the BIOS but it's still going wrong. Borrowing a graphics card from a friend later today, but I can't try my graphics card in another machine because it's too big for any of my friends' cases

Also, if I buy with Next Day Delivery from OcUK, is it (replacement graphics card if needed) likely to arrive tomorrow, with it being a Saturday and all?

 

[Purgatory]

The PSU is an OCZ ModXStream 700W. I've reset the BIOS but it's still going wrong. Borrowing a graphics card from a friend later today, but I can't try my graphics card in another machine because it's too big for any of my friends' cases

Also, if I buy with Next Day Delivery from OcUK, is it (replacement graphics card if needed) likely to arrive tomorrow, with it being a Saturday and all?

That PSU should be fine mate unless it has gone faulty, you will have to pay for Saturday delivery mate not next day for a Saturday delivery, it works great and OCUK always have delivered, just make sure to ask for a Saturday delivery option it will cost a little more but worth it when you can't be in threw the week or really need it for the weekend.

Also you can try the graphics card on your friends pc if he/she does not mind you building their rig outside of the case for a test. You are doing the right thing to try another graphics card 1st that may hopefully allow you to see where the fault is then, but do make sure to test your 5870 because the new card you get may not use as much power as the 5870 and if the machine works it could still mean a faulty PSU that can't now power a more powerful card like the 5870.