After waiting for weeks for the Chinese to deliver some sort of sign that they were planning to ship the PCI-E risers I ordered, we tried Amazon instead and had them delivered after a couple of days. That meant that we were ready for the second part of building the Ghetto rig. But first a look at recent events…
The last couple of weeks has been interesting
Whats behind the plunge in the graph? Lots of things. ETH was up over 5 000% this year when it hit the all time high around $400 so part if this might be the market making a needed recovery. Early investors are bound to cash in sometime. Also, the ETH price follows its big brother currency Bitcoin closely and recent worries in the Bitcoin community about a possible split and protocol changes affected the whole crypto market. The price is up 33% today at the time of writing, so the next couple of days should be interesting, specially from a trading perspective.
Mounting the risers to the Ghetto miner
But we are not trading right now, we’re mining! We headed out to a hardware store to buy a normal wooden board with the dimensions 20 cm x 100 cm x 2 cm to have something to mount the risers on. We reasoned that wood is cheap, sturdy and easy to work with. It worked out well! I sawed it off to give each riser (and GPU) 10 cm. Pro tip: before screwing anything together, measure it out properly so the cables from the motherboard and PSU will reach the cards.
We fastened each riser to the board with two screws, four seemed like overkill for the job. To mount this glorious looking GPU board to the mining “case” we drilled two 4 mm holes through the case and the board and screwed it together. This brought some much needed stability to the rig.
Mounting the cards to the risers
Now we are getting close. Just put the GPUs in their risers and hook up power to the riser and the GPU. We got SATA power cables with the risers but after reading this post on Reddit we were not going to use them. The risers themselves had molex connectors so we just hooked them up directly to the PSU.
You might have noticed that we only mounted four of our six cards, and that’s because we haven’t solved the PSU situation yet. The Corsair RX750 we have right now only supports 4 PCI-E cards and it would probably not handle the power load from six cards very well either. But four out of six ain’t half bad and it will be easy to mount the other two cards later since the riser board is prepared for it.
We figured that we needed to manage the heat between the cards so just like last time we slapped some case fans right on to the cards with zip ties. This turned out to be very effective with pushing the hot air out.
The moment of truth
Everything was in place, time to hit the button!
Goddammit that’s not what you want to see after a couple of hours working, obscure error messages when trying to boot up. It also said it couldn’t find any keyboard before jumping to that message.
We pulled out all of the risers and booted up without any GPUs (the HDMI is connected to the Intel card on the motherboard) and it worked. I remembered that I read somewhere that you should enable 4G Decoding in BIOS when hooking up many cards to the motherboard, so we did that. Then we installed one card at the time. On card 3 we got a Blue Screen of Death, but hopefully that was just a one time thing while Windows were figuring out what the hell we were doing with so many GPUs. Anyway, all four cards were successfully installed and up and running!
Time to see what this thing could do. We loaded up our mining profile with MSI Afterburner and fired up Claymores miner. We usually mine with Genoil but Claymore is better when testing things out since it outputs easier to interpret hashing speeds.
And there we go. ~90MH/s hash rate and each card using ~80w. Interestingly the cards were running a couple of degrees cooler (54 C – 58 C) than in the first setup. This is probably due to that they are further from each other when mounted to the board as well as the case fans can more effectively push away the hot air.
Next time, installing two more cards and a more powerful (or secondary) PSU.