Well, one of my friends has a PC with this motherboard (ECS G31T-M) with an E8300 installed.
I have in mind to upgrade from E8300 to Core 2 Quad Q9450, but there is conficted information on ECS's site: --> LINK 1 - Specifications tab notice: " G31T-M is capable to support Core 2 Quad Q6700 G0 and Q6600 G0". - CPU Support says that supports it (even if Q9650)
--> LINK 2 - Manual's page #5 says only Q6600 / Q6700.
Reply to petros32
More aboutecs g31t supports core quad q9450
Going from my memory, the G31 supports all C2Qs. Only Nvidia's chipset from the time had issues with the 45nm Quads. The manual is probably just old and not updated. I would make sure to update the bios before you put the new chip in. I also wouldn't spend much on it. $10-$15 at most.
Reply to 4745454b
As you say, the CPU support page reports every stepping of Q9450 is validated to work, and even tells you which minimum BIOS is required.
When the manual was printed, the 45nm chips hadn't been validated yet. They have been now.