Since ECS G31T-M7(V1.0) is built with Intel G31 chipset which supports FSB 1333/ 1066/ 800MHz (333/ 266/ 200MHz) but NOT 533MHz, the M/B won't boot up when a FSB 533MHz CPU is installed.
It is a normal behavior due to the chipset limitation.
No. This motherboard cannot support Intel Pentium D 820 CPU. Please refer to the CPU support list of G31T-M7 V1.0 on the following website.
The PCI-E Express specification of G31T-M7 comes with PCI-E V1.1, You can refer to the manual on page18.