**Tech stuff about the rig:**
MSI Z87-G45 Motherboard (LGA 1150)
Intel Celeron G1830 (53W TDP)
Cosair Vengeance (Blue) PC1600 Ram 2 x 4GB
Crucial M4 64GB SSD
4 x XFX Radeon R9-270X GPUs, Double-D edition.
Corsair HX1050 PSU (1050W, 87.5 12VDC single rail)
2 x PCI-E USB Risers (from Amazon)
8 x Coolermaster Magnaflow 200mm Fans (110 CFM @ 19 dba)
Sapphire Trixx for voltage control only
All 4 GPUs running at 1.112 VDC. One of the four cards were returned to Best Buy because it turns out they had two different versions of the R9-270X. BUY VERSION 4! Version 2.x will not undervolt well and they perform like crap. Once I switched to a 4th version 4, I could run all the cards hard with zero issues. I get an average stable 430-435 k/hash at 1050mhz core with lower voltage. Temps range from 64-71C with ambient room temp of 75 F (Southern California). Cold nights keep these cards in the mid 60s. I do not control voltage in CGminer (tried but it didn't work), but I change it in Sapphire Trixx software. The auto config options in Sapphire on bootup only applies to the first card. Upon restart, I need to manually load Profile 1 on each card and hit apply to get them all at the desired voltage prior to mining. Luckily I do not need to restart this machine much, it never crashes on me.
Here's the batch file (when I don't set thread concurrency manually, the auto config had more stable results and no errors):
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer.exe --gpu-reorder --scrypt -o stratum+tcp://stratum.whatsyourdogepool -u user.workername -p password -g 1 -w 256,256,256,256 -I 18,18,18,18 --gpu-fan auto,auto,auto,auto --temp-target 75,75,75,75 --temp-cutoff 88,88,88,88 --gpu-powertune 20,20,20,20 --no-submit-stale