Author Topic: Problem with a 10 GPU mining rig  (Read 3108 times)

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Offline lnabergallTopic starter

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Problem with a 10 GPU mining rig
« on: February 03, 2014, 07:31:33 AM »
So I have setup a 10 GPU litecoin mining rig, but I am encountering a crucial problem. Let me begin by describing the setup.

I have two Gigabyte GA-990FXA-UD3 motherboards attached to a hand-crafted wooden skeleton. Motherboard 1 has an AMD Athlon II X2 3.4 GHz CPU with a single 4 GB stick of G SKILL DDR3 1600 RAM, while MB 2 has an AMD Phenom II X6 3.2 GHz CPU with identical RAM. Attached to each of the motherboards' PCI-E slots, save the 2nd x1 slot on each, are 5 PowerColor PCS+ AX R9 270X GPUs, each connected via a 1x to 16x powered riser cable. Additionally, each motherboard has a Western Digital VelociRaptor 160GB HDD connected via a SATA cable. There are 4 PSUs in total; 3 XION AXP-1000K14XE 1000W PSUs, which each have four 6+2 pin PCI-E connectors, and 1 Sparkle R-FSP1000-50TGM 1000W PSU which has eight 6+2 pin PCI-E connectors.

Power is distributed as follows. The Sparkle PSU is only handling 4 GPUs, three from MB 2 and one from MB 1. A power supply tester is also attached to the Sparkle PSU's 24 pin cable and it's 8 pin CPU power cable to complete the circuit. A single XION PSU is also connected to MB 2, handling the motherboard, CPU, riser cable, and HDD power, as well as 2 GPUs. To MB 1, two XION PSUs are connected. The first PSU handles the power of the motherboard, CPU, 2 riser cables, HDD and 2 GPUs, while the second PSU handles 2 GPUs, their associated 2 riser cables, and the riser cable of the 5th GPU.

I turn the rig on by using a pair of metal scissors to jump the power pins on both motherboards and then immediately turn on the auxiliary Sparkle and and XION PSUs which are not directly connected to the motherboard. I shut off the rig by first shutting down both motherboards through Windows and immediately proceed to manually turn off the auxiliary PSUs.

On MB 1, I have installed Windows 7 64-bit Ultimate and utilize a single instance of cgminer 3.7.2 for mining. On MB 2, I have installed Windows 8.1 64-bit Pro and utilize identical mining software. The .CMD file for cgminer used on both motherboards contains the following text:

setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer --scrypt -o newbielink:http://miningsite.com:3333 [nonactive] -u username.workername -p password --thread-concurrency 15232 -I 18 -w 512 --lookup-gap 2 --gpu-powertune 20 --failover-only -o newbielink:http://miningsite2.com:3333 [nonactive] -u username.workername -p password

The problem began when I had a different eight 6+2 pin PSU, one with 750W capacity, taking the place of the Sparkle PSU. I briefly was able to get all 10 GPUs up and working, but then when I had to restart the rig, Windows and cgminer only registered 4 GPUs per motherboard, despite the fact that the fans of all 10 GPUs were spinning. After another restart to attempt to fix the problem, the number of registered GPUs dropped to 2 on MB 2 and stayed at 4 on MB 1, with all fans spinnning as previously.

After recognizing that only the GPUs connected to the eight 6+2 pin PSU were not being recognized, even after swapping this PSU's position with the others, I decided that the PSU must be faulty somehow so I ordered the Sparkle, with more wattage, and RMA'd the other PSU. Unfortunately, the Sparkle has gone through an identical process. First all 10 GPUs were registered, then it dropped to 4 on either motherboard, then to 2 on MB 2 and 4 on MB 1, indicating that the Sparkle PSU is experiencing similar problems.

At this point I am skeptical that both PSUs have managed to fail, and I am fairly confident that 1000W is more than enough for 4 270Xs, so I am unsure about how to resolve this dilemma. Does anyone have any potential solutions for this problem? I would greatly appreciate it.

Let me know if any part of the setup or operation of this rig needs clarifying.
« Last Edit: February 03, 2014, 07:49:32 AM by lnabergall »


Offline Oldgamer

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Re: Problem with a 10 GPU mining rig
« Reply #1 on: February 15, 2014, 05:45:10 AM »
Frankly, I don't like when not absolutely identical PSU working in parallel and I  believe this is happening, the video cards on the same motherboard connected to different PSUs, which can lead to some troubles.

 

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