Please recommend a small PC - Mesa 5i25, 7i76

I bought this machine a couple months back:
forum.linuxcnc.org/12-milling/29997-brid...epper-to-servo#66035

It came with a decent size tower PC that's overkill for it. It's also taking up valuable floor space and getting covered in chips and coolant where I current have to put it.

I'd like to find a relatively cheap, small PC to replace it. Ideally something I can mount in the cabinet or at least on/behind the machine. As a bonus, I'd like to free up PC that came with it because it'll handle the CAD/CAM work better than my current home computer.

I've read most of the tech on PC selection and have a decent handle on what's needed. I've run the latency test on a couple of my spare laptops and most failed (though I've been told that since it's not using software stepping) - but the PCI mesa card kind of rules out a laptop.


So....can anyone point me toward a decent, small office PC that will work well with my setup? Ideally something I can pick up cheap on CL or Ebay would be great.

Almost any PC from the last 10 years or so is likely to be OK as long as its BIOS allows you to disable any power saving options.
Off lease DC7800/7900/8000/8100/8200 HP SFFs are often available quite cheaply and work fine

Avoid the USFFs as they have no PCI slots so not for 5I25s (though OK for Ethernet cards)

For a new (fanless) system, the J1800 and J1900 based Mini ITX boards in a low profile case are smaller then the SFFs above
and will work with the standard LinuxCNC Wheezy based distribution. The newer (also fanless) J3355 based motherboards also work with Wheezy (the quad core equivalent of the J3355 boards (J3455 based) may also work but I have not tried)

Here's a J3355 MB I just tried with wheezy:
www.newegg.com/Product/Product.aspx?Item=N82E16813157726

I like the concept, but looking at the cost it looks like I'd spend about 3x as much for the DC boards as I would for something like PCW posted above you.

I looks like I could go with that setup - $56 for the board and another $20 or so for a stick of ram and probably a PSU if I don't have one that would work. About $100 and I'm good to go. I already have a spare SSD that I plan to use in place of the HDD in the current machine.

I do like the idea of mounting it right inside the cabinet and that would be my preference. I have concerns about it picking up noise from the other stuff in there - should I be worried about that? I'm currently getting some random button presses that the PO suspects may just be the cheap USB keyboard picking up interference somehow - still need to try another keyboard to rule that out. I'd hate to see it get any worse though.


My goal here is cheap and functional. I don't have plans to use this for anything other than running the mill so I don't see much benefit in getting anything "extra" beyond what I need to run the machine. I don't even have network access in the shop at this point so I don't even need basic internet browsing ability.


Planning to do a little more research on the J3355 type boards posted above, but I'm leaning that direction.

It does seem like there's plenty of opportunity for some stray signals to mix thing up. I know someone else I've talked to that built a similar machine said he was able to solve a lot of it but putting ferrite chokes on everything. That's a cheap enough solution if that's all it takes.

My box is also huge and begging to be tidied up a bit. I may be able to move some stuff around to get some better isolation from the PC or even possibly construct a big of a cage around it to block some noise. Worst case, it won't kill me to mount it in a case outside the box if it comes down to it. I just really want to get rid of the big tower I currently have.

In general you are probably better off noise wise if you put the PC into the control box
since you will have fewer issues with ground loops.

Then just make sure that the 7I76/5i25 wiring is kept away from noise sources (line power, VFD/servo/steppermotor wiring etc)

Alright, any difference between the J3355B you posted:
www.newegg.com/Product/Product.aspx?Item...13-157-726-_-Product

And this J3355M?
www.newegg.com/Product/Product.aspx?Item...13-157-730-_-Product

Looks like the 2nd one takes full size memory and has 2 addtional PCIe 1 slots. Any benefit to one over the other?

While I'm asking - is there any reason to go for more memory or is ~2 gigs enough?

heh....there's my answer! Didn't even notice the micro/mini in the title. Although I can probably fit either, smaller will be better down the road if I try to consolidate to a smaller box.