New GPU computing system (experimental)

Originally Posted by M344587487

Why would the board need 16 connectors? The 8 pin power cables go directly from PSU to GPU, the power connectors on the board next to the slots are to supply 75W from the PCIe slot. I don't get why the 8 connectors lining the bottom of the board from your link exist.

Have you seen the photo ?


The mainboard has 8 power connectors and the PSU cables connect directly to the mainboard. Then there are 8 output connectors on the mainboard.


https://ae01.alicdn.com/kf/HTB1VgwAm...kq6z4tFXa3.jpg

[M344587487]

Originally Posted by SELROC

Have you seen the photo ?


The mainboard has 8 power connectors and the PSU cables connect directly to the mainboard. Then there are 8 output connectors on the mainboard.


https://ae01.alicdn.com/kf/HTB1VgwAm...kq6z4tFXa3.jpg

I see the picture. The eight input connectors supply 75W each to the PCIe slots. Any additional 6/8 pins the GPU requires should use cables directly from PSU to GPU if possible. Now that you've clarified that the other 8 are outputs it makes sense, they exist so that cheaper PSU's with less connectors can be used by splitting the input power between PCIe slot and a 6/8 pin, which is not ideal but fine for anything but high draw cards. If the R7 works in gen 2 slots I see no reason why it wouldn't work on this board, just do PSU to mainboard input for PCIe slot power, PSU to GPU for the two 8 pins, and forget about the outputs on the mainboard.

Originally Posted by M344587487

I see the picture. The eight input connectors supply 75W each to the PCIe slots. Any additional 6/8 pins the GPU requires should use cables directly from PSU to GPU if possible. Now that you've clarified that the other 8 are outputs it makes sense, they exist so that cheaper PSU's with less connectors can be used by splitting the input power between PCIe slot and a 6/8 pin, which is not ideal but fine for anything but high draw cards. If the R7 works in gen 2 slots I see no reason why it wouldn't work on this board, just do PSU to mainboard input for PCIe slot power, PSU to GPU for the two 8 pins, and forget about the outputs on the mainboard.

I suspect that is electrically dangerous. So I use it specification-wise.

[M344587487]

If anything it's more dangerous to split the 6 pin in the first place.

Originally Posted by M344587487

If anything it's more dangerous to split the 6 pin in the first place.

I don't understand what you mean. However, the Radeon VII cost 750 Euro each, it is 6000 Euros for 8 boards !!

[M344587487]

A PCIe slot is rated for 75W, 6 pins are rated for 75W and 8 pins 150W, these are the specs that GPUs try to stay under. A card with one 6 pin can draw up to 150W and stay within spec, which if supplied fully from a split 6 pin input would be up to 75W over the spec of that input. Probably not a problem unless you're staying near 150W draw 24/7 and maybe not even then but it is worth thinking about. The mining rigs these boards are designed for typically underclock and undervolt the core of the GPUS to maximise efficiency running the cards well under the draw they were designed for, meaning splitting a 6 pin is less of a concern. Personally I'd use direct PSU to GPU cables for any 6/8 pins but it's unlikely to matter either way.

Originally Posted by M344587487

A PCIe slot is rated for 75W, 6 pins are rated for 75W and 8 pins 150W, these are the specs that GPUs try to stay under. A card with one 6 pin can draw up to 150W and stay within spec, which if supplied fully from a split 6 pin input would be up to 75W over the spec of that input. Probably not a problem unless you're staying near 150W draw 24/7 and maybe not even then but it is worth thinking about. The mining rigs these boards are designed for typically underclock and undervolt the core of the GPUS to maximise efficiency running the cards well under the draw they were designed for, meaning splitting a 6 pin is less of a concern. Personally I'd use direct PSU to GPU cables for any 6/8 pins but it's unlikely to matter either way.

I didn't modify the default parameters of GPUs, everything is on automatic mode so that the system can adjust on its own, this is important when I am not near the system to watch and make intervention.

Originally Posted by M344587487

A PCIe slot is rated for 75W, 6 pins are rated for 75W and 8 pins 150W, these are the specs that GPUs try to stay under. A card with one 6 pin can draw up to 150W and stay within spec, which if supplied fully from a split 6 pin input would be up to 75W over the spec of that input. Probably not a problem unless you're staying near 150W draw 24/7 and maybe not even then but it is worth thinking about. The mining rigs these boards are designed for typically underclock and undervolt the core of the GPUS to maximise efficiency running the cards well under the draw they were designed for, meaning splitting a 6 pin is less of a concern. Personally I'd use direct PSU to GPU cables for any 6/8 pins but it's unlikely to matter either way.

After though it is not wise to put 8 Radeon VII on that mainboard. The GPU computing temperature is around 107C at 21C ambient temperature. The mainboard slots are distant 68mm, and there is thermal-coupling. The GPUs would quickly reach the critical point which is at 118C.

[M344587487]

Originally Posted by SELROC

After though it is not wise to put 8 Radeon VII on that mainboard. The GPU computing temperature is around 107C at 21C ambient temperature. The mainboard slots are distant 68mm, and there is thermal-coupling. The GPUs would quickly reach the critical point which is at 118C.

You wouldn't want to run 8 but even if you only run 4 this board is probably the cheapest way to do it. A slightly messier but more customisable solution is one of those B250 mining boards with 18 PCIe slots (12 usable by AMD) that can be had for £30, but with having to buy a CPU and £2 risers per GPU it only works out cheaper for a rather large setup.

Originally Posted by M344587487

You wouldn't want to run 8 but even if you only run 4 this board is probably the cheapest way to do it. A slightly messier but more customisable solution is one of those B250 mining boards with 18 PCIe slots (12 usable by AMD) that can be had for £30, but with having to buy a CPU and £2 risers per GPU it only works out cheaper for a rather large setup.

The B250 with 12 AMD needs 2 1200Watt power supplies.


But it is dangerous to use them. At another lab, with 2 power supplies on the B250 we had a fire.

[M344587487]

How much power was going through each PSU? Do you really run completely at stock and not even use --setsclk?