Mining Hashrate Wild Fluctuation Issue

[steveminer]

I purchased a used Antminer S7 and was able to download software and join a pool and setup a backup pool.  I love the idea of being part of this and contributing to the success of bitcoin.  I am not very technically savy though so getting to where I am now has taken me a while.  It was so exciting to see my miner go into action and reach 4.7 TH/s but almost immediately it began dropping down to about 1.5 TH/s.  My dashboard shows that it will rise to a peak of 4.k ish and then immediately drop down again.  It does this over and over in a repeating cycle.  The stats show that it is only averaging 2.24TH/s. Of course I don't know if I have failing hardware or if there is some sort of configuration I could look into changing.  Hopefully somebody can offer some troubleshooting advice and someday I hope to be able to pay it forward.  And if I am not posting this in the right area I apologize in advance.  Thanks, Steve.

[lathrodectus]

Login to your miner's web interface and click "Miner Status".

Whats your chip temps?
To my experience this should stay under 65 degrees celcius.
Whats the numbers under the "HW" column?
These numbers fluctuate. Ideally should be zero. Over a period of 12 hours i see anything around 8 to 35 on some boards. One of my board goes around 200. Most of them are 0.
Do you see any "x"s under the "ASIC Status" Colums?
You might see this very rarely. If there are many present your chips are probably fried.

[BitMaxz]

If your miner is too hot or high temp you can experience of drop hashrate its just like a computer if your cpu is getting high temp your computer will slow down..
Can you have screenshot overview with temp and hashing power?
If you are living in cold places or with AC and maybe your problem is the hashing board is damaged..
Look this https://support.bitmain.com/hc/en-us/articles/220872007-Possible-problems-for-Antminer-Troubleshooting-for-S7-S9
And check the number 6..

[fanatic26]

To my experience this should stay under 65 degrees celcius.
Whats the numbers under the "HW" column?

1. The miner is safe to run until 80c. It will not slow down when it reaches the thermal limit it will stop hashing altogether.

2. The HW errors column will always have some number of errors. You will see thousands of errors very rapidly if the hardware is having issues.

3. The 1.5t number you quote leads me to believe that you have 2 boards that are not hashing properly. Each board should run just over 1.5t on its own. i would try and figure out which boards are dropping then shuffle around the cables/connectors to see if the problem is based on the controller board plugs, the connecting data cable, or the hashing board itself.

[VRobb]

What psu are you using to power the S7?

[NotFuzzyWarm]

And, why 'download software'?
They are stand-alone devices with no external controlling software. Only need a browser to access their GUI for setup.
Source of the used s7? Was it ever underclocked or undervolted? If so ya may want to run at a lower speed to see if it becomes more stable.