So I went to check my miner online and noticed it had been offline for 45 minutes, i went to start it again and could smell burning, turned it on and the first gpu caught fire with like a torch like flame where the power connectors are attached!!! Has anyone heard of this? Why might it have happened?!

We are running 4 gigabyte7970's at around 75c and 673kh/s each In an open custom built frame. All the GPU's are on non-powered risers, could this have been an issue? we have a 1500watt psu running them.

Please could i have some advice, this is pretty scary as i also live on the 66th floor of a high rise building and it could have taken the whole thing down!!