My brother wanted to upgrade his computer by installing more RAM memory. His motherboard is a "Rio" motherboard, . It has ddr2 support up to 667MHz. Still, due to availability and pricing, we ended up with 2x2GB A-Data 800MHz ddr2 memorysticks. I had my doubts, but even the vendor assured the speed should not be an issue. The 800MHz sticks should underclock to 667MHz.
But, after installing the memory, his computer won't POST. It's not responding and can't even enter BIOS. What could be the cause? Are there any BIOS settings that one could change before installing the sticks that might help?
Don't know that board but, put old memory back in, start system again. Reboot and enter bios and see what options are available, particularly ram voltage. This is of course base on the fact you checked to see if the board can see 2 gig modules. The underclocking should be automatic but the default voltage is probobly too low.