IP35Pro wont stay on, was working fine?

[BUFF]

Same codes?
PSU?

[discostu]

I have tried with both a Thermaltake Toughpower 750w and a Zumax zu400w, post code 99 mostly but I have also seen shutdowns on 2A.

[BUFF]

9.9. just shows that the mobo has completed it's shutdown sequence - ideally the POST codes before that would help (as the OP quoted).

[discostu]

BUFF: Right, sorry I missed that.
Most of the time the board goes to 2A/2B and then reboots ( -> 9.9.) but I have managed to boot a couple of times and at one time it ran for almost an hour but then it started all over again. I did manage to turn of thermal protection to test if that made a difference but I had no success with that.

[jsjazz]

It does sound like an overheating problem. I had a similar problem with a different setup, after many many days of removing/replacing components it turned out the CPU was overheating! The heatsink was on fine, solid etc, but over the course of a year or so the thermal paste seemed to have dried out/cracked (probably poor quality thermal pad that came with the stock intel cooler). Anyway, after cleaning/replacing thermalpaste everything worked beautifully again. Just something to consider. Good luck.