couple basic questions

3. When you say POS regarding the PC, is that Point Of Sale PC. or Piece Of S#it PC ?
If it turns out that latency is preventing you from getting the speed you need, might want to try the RTAI kernel, that is usually better regarding latency on older PC's, howto on the downloads page.

In #2 above, the POS is a Point of Sale Piece of S$$T. It was called a ShuttleX. That is the one hanging and needs to be replaced. I used it years after my faster 3.2Ghz machine smoked the motherboard under a memory stick. It's latency was never all that good, up around 65us.

In #3 above, that one is just an old Piece of S$$T PC that has to be 16 or 17yrs old, maybe 20. I found a faster AMD64 CPU and put it in a few years ago. It has 8G of memory. I was testing the AMD64 and with virtualization turned off, etc. I am now down to less than 5us of jitter. It found the parallel card and is ready to rock. I want to clone the IDE drive over to a SATA SSD. Then that will be the machine for the larger mill.

I had plans for this older AMD64 PC. I do a lot of testing that runs for days collecting data and I'm just trying to cut power consumption. I have several other older machines I can use just that its a hassle to back them up, etc. and get the adapters working that connect to the meters that collect the data.

Bottom line, until I scrape together something else, I'll use the AMD machine. I wish I could find a PCIE 4X video card to test that didn't cost much. I did some searching on Amazon and they seem to be around 80+USD.

Thanks

Jerry

wait, people keep mentioning the real time kernel, RTAI? I believe that is the one I am running. the kernel name ends in those letters. also, is there a 32bit version I might be running vs 64? and if so, would that help things?
I am running:

GNU GRUB version 1.99-27+deb7u3

Debian GNU/Linux, with Linux 3.4-9-rtai-686-pae

thanks

That's a 32 bit RTAI kernel.

Just another thing to think about, a mesa 7i92t is about $109USD, better value than a 4x PCIe GPU.
Connects via Ethernet, so easy to change computers if things go bust as long as it has a on board\PCI\PCIe ethernet connection. Latency is easier to achieve as only a 1ms servo thread is required. With the right firmware it will plug into your existing BoB that you connect to your existing setup. Step generation is taken away from the PC. No frustrations in trying to source a MB with a Parallel Port or trying to find Parallel Ports that work, which seems to be an issue. Plus you get an extra 17 I/O pins.

May not be the kind of $$$ you may want to throw at it, but IMHO it's a solid way to go and saves a lot of frustration trying to find replacement PC if\when it goes bust.

You can even use a RPi4 or 5 which is a pretty decent reduction in power consumption, but this is extra $$$.

As for the server boards for Linuxcnc, never had much luck, actually never had much luck Xeon Processors, either in single or dual CPU setups, not that I spent a lot of time with them.

One good PC I have experience with is a Lenovo ThinkStation ( I have several ThinkPad's ThinkStations & ThinkCentres in regular use) m72e Tower (not the sff model) with a 3~GHz i5. I actually found this on the side of the road with a Gseries celeron. The only down side with these boards is that they require the Lenovo 26 pin header to DB25 connector, as they did some trickery, pin is connected to GPIO pin on the super IO chip that enables the printer port. Without this cable the Printer Port wont show up in the BIOS.
I'm actually using this with the Parallel Port on my Myford ML7/S7 cnc conversion.