Any good USFF PC's?

No, it had an on board parallel port. It was this one. (Which of course you can't get it anymore.)
www.newegg.com/Product/Product.aspx?item=N82E16813121596

If I were trying to build the same computer now I'd probably try a board like this one.
www.newegg.com/Product/Product.aspx?Item=N82E16813157497

I don't bother with cases at all, just use a 12V supply mini-ITX in the same box as the other interface boards.
An example: goo.gl/photos/yDRKpazqwjperP1R9

Well that is truly thinking outside the box

Tero

Ended up with this MB:

www.amazon.com/Asus-Motherboard-Mini-DDR...150I-C/dp/B0167OVET8

And this case it is USFF:

www.newegg.com/Product/Product.aspx?Item=N82E16811129081

6i25 was easy to fit in. Assembly was easy. I did like this combo. There was also almost ready place for second DB25 connector for Port 1 of 6i25(there was chassis fan speed setup switch behind case, i put it on HIGH and moved it inside case.Also this had space for two 2.5 Hds and slim CD.

Tero

I was sent a spam about these recently:
www.mini-itx.com/~JBC313

Nice and small, and fanless. Only LinuxCNC option is Ethernet, however.

PCW wrote: If you want to use a USFF PC you are probably better off using a Ethernet FPGA card,

For new USFF+Ethernet, this one is nice:

www.newegg.com/Product/Product.aspx?Item=9SIA2F841F7701
as it has dual LAN interfaces

This one also works well:

www.newegg.com/Product/Product.aspx?Item...56-164-024-_-Product

But has only one LAN interface so if you want internet/localLAN access you would need to add a USB Ethernet /WIFI dongle

(many of the tiny PCs have WIFI built in but they almost always cause latency issues where external USB/WIFI or USB/Ethernet adapters do not)

Based on this post, I purchased one of these for my 7i76e Brix GB-BACE-3160 with Celeron J3160 as it is an update to the Celeron N3150 CPU the Zotec dual NIC PC uses.

I've installed the Wheezy Pre-emptive kernel and am running master to get the gantry features.

Once installed, Latency was still somewhat disappointing. After extensive trial and error changing BIOS settings this is what I got down to so I wondered if these latency numbers can be improved
Servo Thread 1047859 Jitter 56631
Base Thread 94504 Jitter 66090

So are these numbers anything to worry about?
Is there anything that can be done to tweak performance?

rodw wrote: Servo Thread 1047859 Jitter 56631

That will be absolutely no problem if you are using a Mesa card.

andypugh wrote:

rodw wrote: Servo Thread 1047859 Jitter 56631

That will be absolutely no problem if you are using a Mesa card.

Some test confirm this is correct.

Using a NEMA 23 stepper motor and a Leadshine DM542A stepper controller I was able to run it at 673 RPM using 40x microstepping before LCNC complained about step length parameters. I did not bother to push it any further.

It worked out to be stepping at 89,720 Hz. This was just a bench test with an unloaded stepper but the measured speed with a digital tacho was spot on against the commanded speed which indicates no missing steps..

Surely, that is enough to satisfy most applications? The additional cost of the Mesa 7i76e is offset to some extent by the cheap USFF PC so it is a good combination.