I just purchased a KK266 Version 1.2 and it will not post. If I let it sit for awhile it will make it through the power-up test, then beep once, and then says check sum error. But after a few attempts, it won't do any thing but spin the fans when I turn it on. Then I have to let it sit again. The heat sink is properly installed. I am using an 1.2 200mhz athlon, kingston pc100 256mb, 400 watt Future Power power supply. The place I bought the power supply stated that it was Iwill and AMD approved and supports athlon. I have set the front system bus jumper to 100mhz. Any ideas what the problem might be? Is there any test to see if it is the motherboard or the CPU?