Operating computers in the cold

I have tried the computer again today and on first startup everything seemed fine. I decided to install it back into its enclosure. To do that however I had to disconnect power so I shut it down. On the second boot it gave me the power supply error beeping.

So this thing is cooked in my opinion.

I have a new idea to fix this issue however. Since my control cabinet is basically sealed all around I don't gget an air exchange from inside to outside except for the computer fan. I have the face of the computer poking out the side of the enclosure now.
If I seal that hole up and just put a computer inside there with a big bag of dessicant in my mind the air will be robbed of all moisture by the dessicant so there is no water to condensate on my next computer.
I'm also planning to put some dessicant into the main electrical cabinet to save the power electronics and mesa cards from too much moisture.

Is that a sound plan?

I think that as long as it gets fed with fresh (moisturized air) it will be saturated too quickly. Probably it's better to put it in a cabinet where the temperature is higher. The higher the temperature the less moisture it contains.
Besides that I think it's more likely that it's failing capacitors. In general industrial computers are more resistant to low temperatures.

I stripped a redbox machine to use parts for my cnc plasma table. It came with a nice little heater I am going to incorporate for just this.

"I think that as long as it gets fed with fresh (moisturized air) it will be saturated too quickly."

My control cabinet is nearly airtight, in my opinion tight enough to stop an inrush of warm, moist air as the weather changes. The computer would live inside the cabinet and only ever come in contact with the same air that has been de moisturized by my dessicant bags.

Also, as soon as spring comes and the average temperature goes up I don't anticipate many issues with this as it worked fine breathing outside air all trough summer and fall
 

Desiccant sounds good at first, but these do "fill up" quickly. I have dozens of these bags in a 3D printer filament storage container. Even though it is completely sealed (with a gasket), all those bags are only good for about a year. Then they all must be baked at 110degC for 8-12h to rejuvenate them; moisture is insidious.

If you try this, place a quality hygrometer inside. Will likely find that the humidity stays low for only a month or so, even with a good seal.

The moisture alone probably is not causing the inability to start. The way most computers and power supplies are designed, just is not favorable to low temperatures. Very few are, because that is not a typical use case for a computer. Section 5.6 of the RaspberryPi4B says that is good down to 0degC - but then must consider whatever power supply is used for it. The characteristics of semiconducting materials changes as temperature changes, so functionality at low temps has to be something designed into it. Once had a quirky home computer that "complained" at 19degC and refused to run at 18.

If it were my machine, I'd put a heater (like a hair dryer on low setting) near the computer, along with a thermostat. Set the thermostat to say 20degC, and just let it warm up until the thermostat starts cycling. Of course need to be careful nothing can get too hot. Warming should take an hour or more - rushing it is not advised; the whole computer needs to warm up slowly. Then run the machine. That may be easier than re-engineering a quirky power supply or replacing the computer.  Unless anyone knows of an industrial-rated computer (and power supply.)  

One Solution is to get a industrial second Hand PC. I have a Beckhoff which i use with my machine for about 4-5years now and Not a Single Problem. And where i live Temperatures are as low as -10C in Winter.