AHHH my Antminer S7 is giving me problems! Please help

[poly24]

First of all thank you for any help! I have been mining "successfully" for a few months and I just made the jump to my second miner (another s7) and that is when things went sideways for me lol. 

I just plugged my second Antminer s7 in today and I'm having some issues and I thought I might ask for some advice. It ramps up to around 3.8 TH/S when I first boot it up but within about 15 seconds its back down to 0. If I reboot and/or change any settings it does the same thing (up to around 3.8 TH/S and then back down) During the 15 seconds of working, it appears as a worker on slush's pool and it adds to my hash rate. But it quickly disappears after 30 seconds or so and when I check the ant miner settings it shows its hash rate is back to 0. It is connected though a internet switch (the same one that my other s7 is hooked up to, and is working properly) and it is plugged into a 250v surge protector that is plugged into a 250v wall outlet (again same one as my other s7). Any ideas??

[poly24]

update: I turned down my frequency from 700 to 500 and it runs stable now. However, even with the turned down frequency, the temps are out of control. I'm getting 81 on 1  board.

[gt_addict]

Have you opened it up and checked if heatsinks have fallen off or if its full of dust and fluff?

[unholycactus]

update: I turned down my frequency from 700 to 500 and it runs stable now. However, even with the turned down frequency, the temps are out of control. I'm getting 81 on 1  board.

It does look like a temperature problem.
Since you already have one miner running correctly, it doesn't seem to be the environment.
You should start by "cleaning" your miner like gt_addict mentioned, make sure your fans are working correctly too.

[poly24]

Fans are working correctly but I will definitely break it open and clean it. I'll let you know how it goes! Thanks so much

[poly24]

Figured it out... My "pull" fan was running at 3700 RPM and my "push" fan was running at 5700 RPM (both at max). I took off the "pull" fan and now it is working perfectly. My only guess is that it was trapping the hot air inside the miner since it was bottlenecking at the pull fan... My mistake but thank you for your help  gt_addict and unholycactus! Now back to making no profit mining bitcoin!!

[gt_addict]

Glad you figured it out  we all love a bit of negative profit mining for shits and giggles