I know that the 775 are becoming obsolete but this is the best scenario for me to be able to build a kick-a$$ system gradually (already have a Q9450).
I need your advice please on a motherboard that:
1- supports my Q9450 and takes at least 16 GB of DDR3 RAM (couldn't find any 775 that accepts more than 16GB, are there any? Even if they don't fit the rest of the below requirements)
2- Supports SLI/Crossfire <- All Gigabyte motherboards I found didn't support SLI only CF, any motherboard that fits point 1 + has SLI support?
3- Preferably with Sata III (couldn't find any 775 with Sata III, are there any?) and/or USB 3.0
1. There never was a socket 775 desktop motherbaord that accepted more than 16 GB of memory.
2. SLI requires an nVidia chipset and such motherboards usually are limited to 8 GB of memory. The EVGA 132-CK-NF79-A1 and the Asus Striker II Extreme support DDR3 and SLI.
3. That doesn't exist on such an old platform. You'll need add-on cards.
If I were you I'd sell the Q9450 and build a new system that meets my requirements.
You're definitely not going to find anything close to that new right now, hell you'd be lucky to find one with ddr2 and 2 pcix16 slots, like the first reply said, sell the Q9450, you should be able to get enough or close to enough to buy a 2500k with that alone (I sold my E8400 for 125$ there only a few months ago) So you could really make the jump with little or no extra cost to yourself.