I have a problem with my X5DA8 and Matrox Parhelia 512 AGP 4X, the system refuses to reboot, when I press the reset button or if the OS wants to reboot the system (both Windows and Linux) my system just freezes. All LEDs on the front panel light up, screen is blank (power save) and it stays like this. The only way out of it is to press the power button for 4 seconds and power up again. A cold boot is never a problem?
You probably have an older Matrox video BIOS 1.4-20 please contact Matrox to get latest BIOS available (2.2-47) at the below link, this will solve your issue. Matrox BIOS
(sysutil_1805.exe).