New mining rig issues and experiences

[ViperGuyMike]

So I just built my first GPU rig. I went with a 1080ti I already had, plus two 1080 FE's I picked up. Since I plan on buying three or four more cards this month, I went ahead and bought some Ubit risers off of Amazon, and a friend and I built a nice open air case as our original idea of running a large tower case proved to be a thermal nightmare. I just wanted to pass along some knowledge we picked up along the way when it comes to building a rig like this...

First, DO NOT USE THE SATA PLUGS!!! We found out the hard way that the SATA cables don't carry enough wattage to power the riser cards. From what I understand, the graphics cards can pull as much as 75 watts from the motherboard, but since the graphics cards are plugged into the riser cards instead, the riser cards need to supply this power. From what I read, the SATA cables can only supply around 50-55 watts. How we discovered this was after fixing a couple other issues to even get the rig booted, the rig kept crashing when we would begin to mine. Once we dropped the GPU voltage, the rig did better but still had issues. Once we identified the problem and plugged in the molex connectors instead, the issue went away. I was told that the molex connectors supply up to 135 watts. Since you are pulling alot of amperage through these cables, try and only plug in one or two cards on one rail.

Second, once we powered up the rig, we had no video signal. We discovered that by unplugging all the risers from the motherboard and using the onboard video, we got a video signal. Then we shut down, plugged in one riser, and rebooted the machine. Windows took a minute and then saw the card and installed the drivers. We then shut down and plugged in the next riser and rebooted to let windows install the drivers for the next card. We then shut down and did the third card. It seems that you are required to use this method with Windows? Now we were able to boot with all three cards and mine successfully.

After we figured out these issues, we were able to start mining without further problems. The rig seemed a little slower with the risers compared to when the cards were plugged directly into the motherboard, but the open air case allowed us to increase voltage and overclock to achieve higher hash rates than we were seeing with our tower case. We spaced the cards about two inches apart from each other to help with cooling. The 1080ti FTW3 card happens to vent some hot air out the back, so we ended up moving it to the end of the case so it doesn't blow hot air right onto the 1080 FE cards. This helped with cooling as the 1080 next to the ti originally was running warmer and slower due to getting all the ti's hot exhaust.

For reference, we are running all three cards at about 90% tdp. We also used an MSI Z270 motherboard we had laying around with a liquid cooled i5-7600K cpu and 16gb of ram. This is all powered by an 850watt psu with no issues. We chose to run Win10 for the simplicity, and have been trying to decide between NemosMiner and AwesomeMiner. I hope our lessons learned can help others that see this. And please let me know if anyone has any comments or suggestions, especially with the mining programs.

-Mike

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[jillscarbrough]

-First-
Fact: PCIe 16x on Motherboard will supply max 75 Watts, PCIe 1x on Mobo will supply max 55 Watts. Molex connector will supply max 75 Watts to riser and SATA connector will supply max 55 Watts.

So, if we are using Molex connector, will be same as put it directly to 16x PCIe on the Mobo. But am not really sure if the USB cable that connects a PCIe to Mobo using PCIe 1x in front and USB at the end, would supply 25 Watts or not. If yes, 50-55 Watts from SATA + 25 Watts from PCIe 1x to USB would be enough to supplying power to the riser.

-2nd-
That's also the method I always use, safer. The setup process will load faster when we put our cards one by one.

[ViperGuyMike]

-First-
Fact: PCIe 16x on Motherboard will supply max 75 Watts, PCIe 1x on Mobo will supply max 55 Watts. Molex connector will supply max 75 Watts to riser and SATA connector will supply max 55 Watts.

So, if we are using Molex connector, will be same as put it directly to 16x PCIe on the Mobo. But am not really sure if the USB cable that connects a PCIe to Mobo using PCIe 1x in front and USB at the end, would supply 25 Watts or not. If yes, 50-55 Watts from SATA + 25 Watts from PCIe 1x to USB would be enough to supplying power to the riser.

-2nd-
That's also the method I always use, safer. The setup process will load faster when we put our cards one by one.

Thanks for the info Jill! Swapping to the Molex connectors definitely solved our issues. At full power of 117% on the 1080ti, it was pulling 311 watts, and now at 100% it only pulls 277 watts. The 1080 FE cards were pulling 195 watts at 120%, and now at 100% are pulling 178 watts. Also, we had the core clock on the 1080ti at around +99mhz but had issues and had to drop it down to around +60mhz for stability. It still sees over 2000mhz at some points. Our 1080 FE cards were at +250mhz, but were causing ccminer to crash after a while on certain algorithms, so we chose to back them down to +212mhz and haven't had any issues at all since. The 1080's see as high as 2050mhz sometimes.

EDIT: We later backed the cards all down to 90% to help with the heat in my office. They still hash at close to the same hash rate as before.

[philipma1957]

-First-
Fact: PCIe 16x on Motherboard will supply max 75 Watts, PCIe 1x on Mobo will supply max 55 Watts. Molex connector will supply max 75 Watts to riser and SATA connector will supply max 55 Watts.

So, if we are using Molex connector, will be same as put it directly to 16x PCIe on the Mobo. But am not really sure if the USB cable that connects a PCIe to Mobo using PCIe 1x in front and USB at the end, would supply 25 Watts or not. If yes, 50-55 Watts from SATA + 25 Watts from PCIe 1x to USB would be enough to supplying power to the riser.

-2nd-
That's also the method I always use, safer. The setup process will load faster when we put our cards one by one.

Thanks for the info Jill! Swapping to the Molex connectors definitely solved our issues. At full power of 117% on the 1080ti, it was pulling 311 watts, and now at 100% it only pulls 277 watts. The 1080 FE cards were pulling 195 watts at 120%, and now at 100% are pulling 178 watts. Also, we had the core clock on the 1080ti at around +99mhz but had issues and had to drop it down to around +60mhz for stability. It still sees over 2000mhz at some points. Our 1080 FE cards were at +250mhz, but were causing ccminer to crash after a while on certain algorithms, so we chose to back them down to +212mhz and haven't had any issues at all since. The 1080's see as high as 2050mhz sometimes.

EDIT: We later backed the cards all down to 90% to help with the heat in my office. They still hash at close to the same hash rate as before.

I have found 117% 100% settings  to be not very practical .

90%  is better  then the 2 above.

I prefer 70-80%  myself