Three GPUs – one slot. – sunless.cloud

Three GPUs – one slot.

I’ve been interested in cryptocurrency mining for a while now, and although Etherum is slowly coming to an end I’m hoping there will be a profitable replacement.

My rig is built on a “Z390 D Gigabyte” motherboard with a “4 × Intel(R) Pentium(R) Gold G5420” processor. The motherboard has 3 x PCI-E x16 full slots and 3 x PCI-E x1. It handled 6 cards until recently: 5xRX580 8GB and 1xRX570 8GB. As it sometimes happens, there are unexpected accidents, and so mine seems to be an not isolated one. Well, one time I got tired and tried to connect the rig to monitor to see why I couldn’t connect via ssh (I had to fsck ssd) and unfortunatelly plugged one riser in reverse to x16 slot. There was no visible smoke and the system was on like that for about half a minute. The riser end was pretty damn hot. Fortunately the card didn’t get hit, surprisingly the riser was unharmed but the x16 slot got fried. I was left with five slots and seven cards (one additional RTX3060ti). New motherboard costs about 120$ and with more slots they are even more expensive.

I bought on ebay pci-e splitter (link) for $20. My goal was to connect all seven cards to the five remaining slots. From info from the processor specs page it looks like my processor supports up to 16 gpu’s. At first try with seven cards the rig powered up but there was no welcome screen and no way to access the bios – just black screen. To achieve my goal I unplugged all the cards and plugged one into working x16 slot. In the bios I had to search for the following settings: pci-e bifurcation and pci-e speed.

I changed the “Auto” settings in the bios to the following:

  • pci-e bifurcation – x4/x8/x8
  • pci-e speed – Gen1

The system has been running stably on seven cards with three connected via splitter for a week at the time of this writing with no loss on hashrate.

PCI-E to USB Adapter 4-port PCI-E X1 to USB 3.0 Riser Card Extender.
Hiveos cards preview.
Miner terminal screen.

I haven’t tried running it with four cards, but I’m happy with the current configuration.