I´m running with about 35 GH/s per stick.

Mine are running at 350 MHz with the arctic breeze fan. The´re getting pretty hot but are working for months now.

That wasn´t the quesition.

Are always the same working and the same dead? Usually it´s a power issue.

12.5 BTC is correct. But there is almost no chance to solve a block while solo mining.
Mining in a pool give you constant payout. But it´s pretty low.
I am making 35 GH/s with one stick. The actual Hashrate inside the network is about 35 EH/s. That´s 35 000 000 000 GH/s. So, if I´m correct here, there is a chance of about 0,000 000 1 % to hit a block with a well running 2Pac.

And in the upper right edge of both sticks you see the pot. But it seems to be set to a good position. Looks like 2 o´clock. So it should run fine at 100 MHz.

Why are you trying to let it run below 100 MHz? 100 MHz should run fine. What position is the voltage pot looking at it on the electronics side with the usb port facing down? Should be at about 2 or 3 o`clock.

The actual values aare not that important if you have no issues. Just increase the frequency and check if it works. If you´re facing any power issues we can check the amps again.

Hello jogger1,
the view is alway on the pot, so the heat sink on the side away from you, with the usb port facing down.
I have no actual amp values. But there is a table with an overview of values in post #1. I had found them not perfectly correct but nearly.
If you want to adjust the fequency up, just do it and check for HW errors comming in. If there are any, turn the pot a bit clockwise until there are no new HW errors coming in. If your hub isn´t strong enough the stick will zombie. That´s the easiest way to check.
But I think at 2 or 3 o´clock 200 MHz should be possible.

Try starting cgminer with the sudo command:

Raspian Stretch lite is just the usual Stretch version without a desktop. I´m using it and it definitely works.

What happens if you try the faulty one alone in the hub? Does it work then?

Which operating system do you use?
Try the newest version of raspian. The commands on post #1 should be up to date.
https://downloads.raspberrypi.org/raspbian_lite_latest

Did you try this?
After that try installing the packages again.
And be sure there are no line breaks inside your command. So be careful with copy and paste.

Try https://wiki.ubuntuusers.de/apt/apt-get/
It´s a good and informative wiki.

Maybe first get the HW errors to 0. Turn the voltage to 4 o`clock and see if there are new HW errors coming. If not you can increase the frequency again.

OK. Then let me know if it worked.

Are you still running one at a time? Are you able to run one alone at 200 MHz at 3 o´clock? I think that 3 Amps isn´t enough for 250 MHz to run stable.
What happens after 24 hours? Do they go zombie?

In my experience putting them into a box isn´t the best solution. I tried this, even with an open case and two fans. They get hotter than with my current setup, open just inside the hub with the arctic breeze fans.

Like I wrote a few times before, I have two 2Pacs. Each one in a 30 W Hub. Both running at 350 MHz. Voltage pot is set about 6 or 7 o´clock. Each one cooled with a Arctic Breeze fan. Both controlled by one RPi with cgminer.

Can you post the cgminer.conf file you are using? Does it have the --text-only option? Or do you start with this option? The option -t is the same? Do you use this one?

Try turning the voltage pot to 3 o´clock with the USB port at bottom and view on the pot. Then set the frequency to 100 MHz. Then set the frequency to 175 or 200 MHz. If there are HW errors coming in, turn the pot clockwise until they stop coming in. Maybe you have set the pot too high already.

I think moste of the people here, me included, have got them running continously. So I won´t say it´s impossible. My oppinion is, it wasn´t even hard. Mine are running for weeks without any issues. Only the PI freezes occasionally. But even that happened once or twice in the last months.

I´d think that 3 amps is not enough for two sticks at higher frequency.
Turning the pot clockwise is setting the voltage up. But this causes higher power consumption. Try both of the sticks alone in the hub. Do they work then?
What happens exactly when they stop working? Do they go into zombie mode?

The discription says:
1.5 A is not enough current for one stick @250 MHz. I don´t know what "depending on power supply used" means. I would buy another one. Make sure there is no limitation on the current per port. In my experience you need about 3 A per stick @250 MHz.