Maybe you have an E7300, not an E7400.
Maybe your motherboard cannot run ½ multiplier steps with your current bios version.
Maybe your bios is just set at 10x rather than the 10.5x an E7400 will run.
It's not the speedstep thingy.
so that mean the highest speed i could get with this cpu on this motherboard is 2.6 then right ?? >< well im using p5ld2-se which is i know don't support this cpu but the guy at the store somehow manage to get it work for me ==" so i dont know is this the reason why it only run @ 2.6 at most ?
During the POST, hit the <delete> key to enter BIOS Setup.
Browse through the menus looking for FSB speed and multiplier settings.
This will get you familiar with what the guy at the store did and what settings are available. Don't worry that you will cause any harm, since you will pay attention to this most important part:
When you are done, select "exit without saving changes" !!!
There is a procedure called overclocking that can make a cpu go faster, but for now I would say that you shouldn't worry about the difference between 2671.6 and 2800 MHz.