I received my review unit from Spondoolies on Monday.
https://bitcointalk.org/index.php?topic=887807.0 As noted elsewhere, the unit was packed nicely. I appreciated the all-cardboard packaging which is fully recycled where I live.
EnvironmentSince I'm cold blooded, I like my place warm. Really warm. My old BitFury miners also love the heat. Let's see how the SP20 fares.
SetupMy Antec HCP-1300 Platinum 1300W PSU was ready and waiting. Most PSUs have a color coded mb connector wires, but this one has all black wires. I grabbed what I thought were the right two pins and plugged in my paperclip. Lights come on and the SP20 connects to the network. Must be the right two pins, right? I surf to myminer.io and see my machine up and running. I click on it and go to the Pools page and input my pool credentials. But the miner just won't mine. It's only using 4 watts and the supposedly loud fan isn't spinning. It finally occurs to me that the paperclip might be in the wrong pins. I switch to the right pins and this time the fan lets me know I found the right pins.
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TweakingMy BitFury miners are quite tweakable, but it's very difficult to do so (adding/removing cards, editing config files). But their modularity and tweakability allows me to maximize my hashrate per electrical circuit. While not modular, the SP20 allows very easy tweaking of voltage and power. Here are the results. All tests at 100% fan and 40c intake temperature.
| Voltage | Wattage at wall | GH/s |
| .65 | 710 | 1240 |
| .70 | 1005 | 1468 |
| .75 | 1110 | 1520 |
| .79 | 1150 | 1534 |
Since my PSU is more than sufficient, the limiting factor in performance is the temps. The SP20's single exhaust fan just doesn't move enough air when in a hot room. Half the chips get hot air from the other half, like the old dual GPU 5970, so they get clocked down significantly. I wish there was also an intake fan on the other end for a nice push-pull configuration. This would also lower fan noise, although noise is not a concern for me. A half-size SP20 where the airflow goes over a single set of chips would also work well.
SummaryThe SP20 excels in quality construction and ease of setup. Provide a good PSU and turn it on. It'll adjust itself for maximum performance, even in a hot room. Later when efficiency becomes more important, lowering the voltage will come in very handy. Recent price drops by Spondoolies make the SP20 one of the best buys in the market.
