AOpen AX3L User Manual page 27

Hardware Installation
III. Buffered and non-buffered: This motherboard supports non-buffered
DIMMs. You can identify non-buffered DIMMs and buffered DIMMs
according to the position of the notch, following figure is for your reference:
Reserved
buffered
Because the positions are different, only non-buffered DIMMs can be
inserted into the DIMM sockets on this motherboard. Although most of
DIMMs on current market are non-buffered, we still suggest you to ask your
dealer for the correct type.
IV. 2-clock and 4-clock signals: Although both of 2-clock and 4-clock signals
are supported by this motherboard, we strongly recommend choosing 4-
clock SDRAM in consideration of reliability.
V. Parity: This motherboard supports standard 64 bit wide (without parity) and
72-bit wide (with parity) DIMM modules.
There is no jumper setting required for the memory size or type. It is
automatically detected by the system BIOS, and the total memory size is to
add them together. The maximum is 768MB.
LX chipset can only use 3V EDO or SDRAM, so we can mix EDO and SDRAM.
Every DIMM socket can be EDO or SDRAM. For EDO, maximum is 256MB.
For SDRAM, maximum is 128MB.
Total Memory Size = Size of DIMM1 + Size of DIMM2 + Size of DIMM3
Note: 768MB memory is achieved by using double-sided
buffered EDO DIMMs.
2-16
non-buffered
Tip: To identify 2-clock and 4-clock SDRAM, you
may check if there are traces connected to golden
finger pin 79 and pin 163 of the SDRAM. If there are
traces, the SDRAM is probably 4-clock; Otherwise, it
is 2-clock.