I recently purchased an Antminer S5 on eBay that came with a Corsair GS 800 power supply. I set the miner up, connected it to a pool, and it seemed like it was working fine. After about 15 minutes I noticed that Chain 2 was inactive (status showed multiple '-' on miner configuration page). I restarted the miner, and it was working fine until again after about 2 hours, Chain 2 stopped, but now its status still showed it was active ('ooo'). So I restarted again, and after about 6-8 hours this time, Chain 2 stops, and still shows as active.
Each time chain 2 stops the total GH/s is only about 600.
I'm really confused by this because it seems like the miner is working but something just causes chain 2 to stop. It came shipped with 2 new fans on the front and back, and a frequency of 387.5M (Default is 350). The seller has not been of much help so far. Really has only been telling me to keep restarting it, which works but only for a short time.
Any ideas what could cause this or how to fix?