Advice for choosing a compatible PC

Dear friends i am new here and need an advice.

1. I do have two cnc machines (one profesional machining center and one small 4 axis chinese 3040.
2. In this second hobby machine (Chinese) the controller burn out 2 years ago.
3. It was an opportunity for me, to build a new electronic's box and check if i can make it work with LinuxCNC.
4. I went with a compatible to LCNC controller (a cheap one because it was a test),  new wiring, new stepper drivers, a new 5V paraller card  on PC, Debian installation e.t.c..
5. Was trying too many days to make it work with no result, I gave up and did order a windows USB controller card for mach3. Like it (me) or not, it worked this way and still does.

6. By being unable then, to make my Chinese 3040 to move by LCNC, some months ago i did order a 4 axis USB CNC controller (180€) for the new machine i am preparing (DIY).
7. I am sure it was my mistake buying this controller because it needs a PC. I could give some extra money for a standalone one, but i didn't.

So I need your advice.

I have some old PC's and 3 old motherboards to use, by installing win7 or winXP.
But before that, i want to check them for Latency to choose one of them (or none.....).

There is a win application called LatencyMon at www.resplendence.com/downloads.

Its the closest (to Latency Test), application for windows, i could find.
But i believe it is way better to test these PC's and motherboards,  by the real Latency Test, booting from a USB on a LINUX version with LinuxCNC and run Latency Test.

a. If you agree with that, please inform me for a Linux Version with Linux CNC to use?
b. Is it ok to make a bootable USB  to avoid instalation or LatencyTest's results may differ from actual measurements?
c. Does Linux version has something to do with the hardware of these PCs, specifically for this test (hardware drivers, e,t,c,) ?

Thanks in front
Evangelos

P.S.1   I know the difference between LCNC and everything else but i am doing the best i can for now, having in mind to find a way to switch to LCNC when someone can do it for me. The hobby Chinese is there for more tests on this.

P.S.2   My PCs and motherboards if needed are.
1. MSI P45 NEO3    MS-7514 Ver:1.1   Intel® P45+ICH10R
2. Prescott 800    P4i65G (ASRock)   Socket 478 for Intel Pentium4 Celeron 865G  E8000 Series Chipset
3. MSI  K7T Turbo Ver:3 MS-6330    Chipset:VIA VT82C686B - K7 Athlon Duron
4. Dell Dimensions OptiPlex GX270    Foxconn LS-36   Intel 865G   
5. HP compact DC7600 Intel® Pentium® 4 
 

I would ignore any old 32 bit PC's you have. I originally wanted to use one when I started 7-8 years ago but found I had to buy a new PC. My recomendation is to use a 4 core 64 bit Celeron or above. Eg J1900 and later.

Controller card is this : www.ebay.com/itm/164626076182
Thanks for your help.

First, if you want to work with LinuxCNC, you have the wrong controller. This is a mach3 controller. If the controller works well, it will not be affected by the latency of the computer.

You could have bought a 7i96S controller.

Yes it is a Mach3 controller, it is the only software i can install so far.
It has also good recommendations from people using it.
And no one has mentioned anything about selecting a specific PC for this controller.

So your comment "If the controller works well it will not be affected by the latency of the computer" may be correct.

I prefer to do a Latency Test either way while i dont trust windows to handle my machine.

In my mind is not a black or white matter a windows based CNC.
I prefer to eliminate the risk until i am able to switch to LinuxCNC.
Thank you
Your comment was useful.

I want to clarify something here. What you linked to is a motion controller in its own right. Windows is not able to operate in real time so the MAch solution was to delegate motion controll to external hardware running on a small not very powerful embedded controller of some kind.

This contrasts with LinuxCNC where LinuxCNC is the Motion controller. The CPU on the PC has vastly more processing power than the Ma the ch board. We are talking orders of magnitude of more power. But this implies that the dumb eternal hardware used by linuxcnc must be capable of real time performance which typically means it can handle 1000 updates per second. The USB bus is currently not capable of operating with this real time requirement. SO your hardware is useless for Linuxcnc.

This looks a bit sus, seems to be a change in the quoted text regarding the link.

I would like to thank you Rodw and thank everyone for their help.
Your comments gave me some informations i was not expecting..

a. BesriWorld wrote above, "If the controller works well, it will not be affected by the latency of the computer."
It is correct finally but i didnt know why.

The following Research cleared to me the way this setup is working, in paragraph 2.
www.researchgate.net/publication/2716157...nd_Motion_Controller.

In paragraph 2 says
"GT400-SV motion control card is embedded in the PC machine through the PCI slot.
Motion control card's CPU and PC's CPU as master-slave dual CPU control mode.
PC front end management for non real time tasks, such as man-machine interface, and other functions.
GT400-SV for real-time tasks, such as interpolation, servo control, I/O etc"

This confirms why Latency for this setup PC+Motion control card is not important.

b. You wrote that a PC with LinuxCNC has vastly more processing power than the Mach board. and its so true.
Why?

My motion controller has 120M working frequency and maximum step-pulse frequency at 1 Mhz
120M = 2.5Mhz. .

PC with J1900 proccesor has 2Ghz perSec.
or
650 MemoryOperationsPerSec on each of its 4 Threads.
2Ghz=800*2.5Mhz,
Even Ferrari vs Tortoise is 340Kmh/*0.5Kmh=680.

No other comment.

P.S.If anyone can suggest me a good motion control card for Linux CNC, i will set the machine in windows for now and will bye the card to change everything as soon as i can.
Sorry for my English and Thank you again.
Evangelos