Aaeon SBC-555 Manual page 23

JP1 must be set to match the CPU clock ratio. The chart below
show the proper jumper settings for P54C, P55C, and AMD-K6,
and their respective clock ratio.
P54C x1.5
P55C x3.5
AMD-K6 x3.5
5
6
3
4
1
2
AMD-K6 x5.5
5
6
3
4
2
1
SBC-554V/555 supports 5V DRAM and 3.3V DRAM. JP-2 must
be set to match the DRAM type.
3
2
1
P54C x2.0
P55C x2.0
AMD-K6 x2.0
5
6
3
4
1
2
AMD-K6 x4.0
5
6
3
4
1
2
P54C x3.0
P55C x3.0
AMD-K6 x3.0
5
6
3
4
2
1
AMD-K6 x5.0
5
6
3
4
2 1
3
2
1
P54C x2.5
P55C x2.5
AMD-K6 x2.5
5
6
4 3
2
1
AMD-K6 x4.5
5
6
3
4
1
2