Dell Dimension 3000 latency issues

The P4 I have was only able to do about a 30.000us base thread, when I was still software stepping. (It has a Mesa 5i25+7i85s now)

Sometimes adding or having the right graphics card can help with these old P4s.
My machine has step/dir servos and not step motors, so having fast high resolution stepping was helpful. But on most step motor systems there usually isn't much point in having micro-stepping set higher than about 4.

At this point I am stuck with the 10x microstepping of the G540. It is fixed. If I had known a bit more I might have picked a different controller but at this point I will stick with this at least until I get this running. How would I test out the graphics? I am currently using the on board video. I have a couple other old cards I could try - think they are 5200 series Nvidia or about that vintage. Would shutting down X and doing command line eliminate the video card issue? Maybe run it headless with another network PC acting as the GUI?

Just have to plug them in and see what happens. I've read conflicting things, some say Nvidia are hopeless, others say they work fine as long as you don't use their propitiatory drivers. Old Matrox cards seem to usually work well, as do some ATI. It usually comes down to what will work well with the standard Linux video drivers, and not need one from the manufacturer. A lot of times this means you might not be able to use the full resources of the card, but those aren't really needed, just to run a cnc.

JimS, Have you resolved your problem with high latency on the Dell? I have the same problem. I have tried the v8, v10, and v12 of Linuxcnc (EMC2) on two of my PCs. V8 and v10 have very nice latency numbers but v12 produces very high numbers. I tried another PC that has an Athalon 64 4000+ processor. V8 and v10 are good. V12 is acceptable but on the high side.

I personally don't care which distribution linuxcnc is built on. So if there is a better one then I am happy to use it. I am starting from scratch with a Dell Optiplex GX260 and a HFT 7" lathe. You experiences and input are most welcome.
Merry Christmas

As I reported earlier in this thread, I have installed Ubuntu 10.04 version and upgraded linuxcnc. It works well enough (steps fast enough) that I settled on that and moved on to actually doing stuff with the software. That iso can be put onto a cd so it avoided the problem with not having a dvd drive on the PC I am using as well.

If you have trouble finding this iso file some links and info are here:
www.linuxcnc.org/docs/2.5/html/common/Getting_EMC.html

You findings about 8 and 10 being good and 12 being much worse are similar to mine. I went with 10 as I wanted to be as up to date as possible and still have decent performance. It would be nice to have a bit better performance than 10 (step rate improvement) but at this point the gain isn't worth the work to figure it out, at least for me. And I don't plan to hook the box to the internet so security fixes and such of later releases aren't a concern.

I know it has been months since your last post in the subject. Thank you for responding.
I too intend to dedicate my Dell(s) to machine control and will not be connected to the Internet nor run any program escecially while running EMC2. I was just trying to get the low down on why the latest linuxcnc had such latency problems with my pcs. I too wanted the latest features and bug fixes. However I have no problem if the answer is ... Well some pcs just won't run the latest version! What I didn't understand was the answer I was getting which was ... It's the kernel of that version when run on a single core processor. I was confused because I tried three pcs and three versions of linuxcnc with results that pointed to two of the PCs being the problem.
So, like you, I am going to use the two Dells to run a simple lathe and a mill. I'll use the linuxcnc version under Ubuntu v10. For my more complex project I'll acquire or build a PC that will best take advantage of the latest version of linuxcnc without digging into the guts of the software.
I appreciate you time and consideration
Best of luck