Dell Optiplex 580 and LinuxCNC - viable?

I have been gifted an Optiplex 580 SFF. Key internals are:
CPU: Athlon II X2 B26 @ 3.2Ghz
RAM: 8GB
BIOS: A08

On board ATI RS880 (Radeon HD 4200)

Has anyone used one of these machines on LinuxCNC before with success?

If so any advice on how to configure them? I have been fighting with this for a few days now and do not seem to be able to remove or track down latency spikes that push the latency test into the 900k mark. Looking at the latency plot these spikes are very clear and happen anywhere from every 60 to 90 seconds.

Thanks for any available wisdom/advice,
James.

Here is a little more information that might help trigger an idea with someone who has "been there done that".

Here is a sample latency-plot. This pattern is pretty typical of what I have been getting with all the various parameter tweaking done to date. I have tried the most of the boot params that are talked about (cpu isolation, nohalt, poll etc) as well as stopping all power saving/management including on the inbuilt video. I have also turned off all the non essential onboard devices. I have not yet tried a PCI-e video card, mainly as i need a half height unit to fit and the only spare I have is a monster power hungry HD5850. Heck I don't have anything light weight enough to fit into this so would be looking at buying something specific for an experiment.


I thought I would dump in an lspci just in case it is of use.


Cheers,
James.

Thanks Andy. I had thought that the SMI issue was specific to Intel chipsets. Is the link you provided viable for an AMD based machine like mine? Or is this a case of “suck it and see”?

Cheers,
James.

No worries.

I have now been able to get a PCI-E half height graphics card and add that to the system. The spikes are still happening. I am starting to suspect that either the AMD chip the motherboard of the BIOS or some combo is just not going to be friendly to the RT requirements. I have managed to source an Optiplex 960 (Core2Duo) machine for NZD120 and run the same tests. Its night and day. The 960 has sub 30k latency with zero tuning done to it other than some basic changes in BIOS to power management and RAID settings.

I'm thinking I need to get a spare 960 to stash away for parts.

Cheers,
J.