Computer reliability and buying a good one.

I used an old P4 dell for two years and after inhaling dust for a long time the PSU roasted the motherboard.
I then proceeded to assembled my backup D945GCLF2 with 60GB Intel SSD, somewhat pricey/high end memory, and with a generic case that has a lower end PSU.
I loaded up the newest precompiled LinuxCNC package and off it went.
It works and with multithreading off I get 10K latency without any further tweaking.
Now I don't like the idea that I'll have to blow the computer out with compressed air every three months since the CPU has a little fan and the cheap PSU has one, but overall I'd assume it's a solid build. But just today I connected a small USB wifi card then computer gave me an error about something involving asci text, memory and there is no boot media. I cycled it on and off some without any luck.
I left it off for some time and now it works. But if it pulls that trick on me again and doesn't work then I can lose a decent amount of orders.
What part of my ultra basic build could be getting me? I realize inserting the card probably started it but how can that cause issues if the computer is turned off and then it persists?
Idealistically there should be no fans to clog with dust or not dust to clog the fans, but this computer has been used for just a month, and is spotless.
Are there are proven solid state computer "builds" or rebuilt setups that have no fans?
I'm getting to the point where if a machine slips up I'm out $40 in material and the cost of a mistake is high.
Finally, for the meantime does anybody know how to connect a PicoPSU to a motherboard that has an extra st of 4x4 pins on the main power connector?
The PSU worked great for a different computer, but it seems that it lacks a few connectors.....

Try checking your BIOS and see if you, like me, have booted from a USB in the past and forgot to change the boot order back. With nothing in the USB slot the system boots from the hardive but with anything in the slot it thinks it's a bootable media, even if it just a WiFi stick. Probably not your problem but it happened to me.

By the way there are some nifty little fanless systems on the market. All of our system at work at completely sealed, fanless units. I'll try to track down the model numbers. On our 'normal' systems we have built some 'boxes' with filtered fans inside to keep the dust out of the computers and this has worked out well. You only need about 1.5-inches of clearance around the sides. Our shop is incredibly dirty since we run water-jets and Laser cutters in a confined space, usually with the extraction fans turned off because we forget to turn them on until it's to late.

The PC currently running my mill is an Intel D525MW which I put into a small and old home theater enclosure. I opened up the PSU, unscrewed the fan and remounted the fan so it recirculates air inside the enclosure over the PSU. I also added an extra fan inside to circulate air inside. Then I taped off every hole in the enclosure.
This works fine; the case metal provides a lot of heat exchange surface area. Temperature inside the enclosure is 5-10C higher than ambient. The trick is to circulate air inside the case.

I did the same with a Celeron G550/Intel Z77 chipset mainboard in a minitower enclosure: mounted the PSU fan on the heatsink inside the PSU, added an extra 120mm fan inside to circulate air, and sealed off all the holes. This works, but heat management is on the edge with inside temperatures raising to 15-20C above ambient. I will add two heatsinks back to back to the case, one on the inside, one of the outside. That should do the trick.

So far the enclosed PC's are rock stable and reliable. Everything with a fan sucking outside air in it's case has a life expectancy of 6 months in my garage.

The enclosed computers on some of our machine are sold by Advantech and use the Intel Atom D525, This seems to be a popular unit with the jet and plasma OEM guys.

I apologize for the late reply..
I had a decent amount of things I have been doing and the machine was operating flawlessly.
Then the computer started freezing, locking up, and doing other nasty things.
I replaced the 60 GB intel SSD with my ancient hardrive from my 8 year old P4 desktop that fried.
Now the computer works, so I guess it was the SSD?
I am going to look into getting an adapter so I can power my motherboard from the picoPSU I own.
Then I'll put some sort of material on all the vents and hopefully that machine works for years.

In the end I have had enough issues I was running off thinking of PlanetCNC, Mach3 with smooth stepper, and all those solutions where the computer doesn't matter.
But the trajectory planning of LinuxCNC is critical (maybe not but the 3d profiling works perfectly so why try anything else?) for what I do and I really wish to stay with it. I am buying a second CNC machine shortly... So what I'll do is buy a DN2800MT, D510MO, or D525MW, then a picopsu, and for the HDD where/what kind of 8GB DOM SSD should I procure? I've had a nice knot in my stomach as I just got the current machine I own working and if I couldn't then I'd be relegated to finding something (on this rock in the middle of nowhere and I mean nowhere) so I can finish a couple orders to pay for another machine

Anyways thanks for your time and patience with everything.
Josh from Paauilo, Hawaii

Is this the SSD? www.ebay.com/itm/Brand-New-KingSpec-KDM-...&hash=item461800108c
I just bought a Microcarve MV3 to accompany my A4, so now I can say I own two CNC machines, and not that PS3 that most in their early twenties own