They're used to move cards apart for better airflow, and to utilize all available slots in your MoBo. You can use 1x extenders for mining too. If you try to connect more than 4 GPU's to a single MoBo, you will need to get molex powered extenders.
1) By "4 GPU's" do you mean 4 vid cards or are you counting the number of actual GPU chips? ie higher end cards have 2 x GPU chip on each card.
2) If running more than 4 GPUs, then do ALL extenders need to be molex powered?
2) Many people don't even use cases, or build something to suit their needs.
I wouldn't daisy chain extenders together to run the GPU's just sitting on the table. They are much safer properly supported.
Yes, I understand that extenders are used to move the GPUs around, although obviously the extended GPUs are not going to be able to fit (be screwed into) somewhere empty on the box's backplane cause they probably wouldn't fit. I gather that extended GPUs are usually just fitted anywhere in the case that there is space.
If many are running PCs without cases, then theoretically the cables CAN go anywhere. I was not thinking of daisychaining 2 extenders to lay all the GPUs on the table somewhere. I was thinking of racking the GPUs/vid cards on some sort of structure outside of the case - definitely fastened & safe in some way. (although I do have plenty of 5 1/4 bay space in my case)
So I guess I'm still wondering if it would be safe to daisychain 2 extenders. I guess I can ask the shops selling these extenders about this idea. Would be good if someone here had an answer though.
Thanks for the info so far..... fascinating topic since I had never heard of extending expansion slots before (and I've worked in IT previously).