Abit AX5 Instruction Booklet page 47

Introduction of BIOS
Normally, we do not recommend that you use the "User Define" option to setup
CPU speed and multiplier factor. This option is for setup of future CPUs whose
specifications are still unknown. The specifications of all present CPUs are
included in the default settings. Unless you are very familiar with all CPU
parameters, it is very easy to make mistakes when you define by yourself the
external clock and the multiplier factor.
/ Turbo Frequency:
This item will only be displayed if your CPU external clock supports
Turbo mode.
The Turbo mode allows you to speed up the external clock by
approximately 2.5%. This feature is used to verify the design flexibility.
It is a very important tool for test units to verify CPU stability. Do not
use this feature.
Solution in case of booting problem due to invalid clock setup:
Normally, if the CPU external clock setup is wrong, you will not be able to
boot. In this case, turn the system off than on again. The CPU will automatically
use its standard parameters to boot. You can then enter BIOS Setup again and
set up the external clock.
When you change your CPU:
The AX5/PX5/TX5 mainboard have been designed in such a way that you
can turn the system on after having inserted the CPU in the socket without
having to configure any jumpers or DIP switches. But if you change your CPU,
normally, you just have to turn off the power supply, change the CPU and then,
set up the CPU parameters through CPU SOFT MENU™ . However, if the
CPU brand and type is the same, and if the new CPU is slower than the old one,
we offer you three methods to successfully complete the CPU change operation.
Method 1: Setup up the CPU for the lowest speed for its brand. Turn the
power supply off and change the CPU. Then turn the system on
again, and set up the CPU parameters through CPU SOFT
MENU.
various brands and types available.
ä Disable: CPU external clock is operating within the
normal limits.
ä Enable: CPU external clock is operating within the limits
of the Turbo mode.
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