ASROCK X38TurboTwins-WiFi Manual página 19

If you use a FSB1600-CPU and adopt a DDR2 1066 memory module on this
motherboard, you need to adjust the jumpers. Please short pin4, pin5 for FSB3.
Otherwise, the CPU and memory module may not work properly on this motherboard.
Please refer to below jumper settings.
If you use a FSB1333-CPU and adopt a DDR2 1066 memory module on this
motherboard, you need to adjust the jumpers. Please short pin4, pin5 for FSB2.
Otherwise, the CPU and memory module may not work properly on this motherboard.
Please refer to below jumper settings.
If you use a FSB1066-CPU and adopt a DDR2 1066 memory module on this
motherboard, you need to adjust the jumpers. Please short pin2, pin3 for FSB3.
Otherwise, the CPU and memory module may not work properly on this motherboard.
Please refer to below jumper settings.
ASRock X38TurboTwins-WiFi / X38TurboTwins Motherboard
FSB1600 / DDR2 1066
FSB1333 / DDR2 1066
FSB1066 / DDR2 1066
1 9 1 9 1 9
1 9 1 9