I upgraded an AMD phenom II X4 840T to an FX-6300, both use A3 socket, so just plug in. Machine will not boot with new CPU, can't seem to find a way to upgrade BIOS, it is Legacy. Old CPU works fine, did CMOS, HP Pavilion bios 6.04...any thoughts ? Needed a CPU with sse 4.2 or later instructions for Photoshop.