Acer R02-A3S1 Motherboard

Hi there i have i think and acer aspire m5100, not in original case!! but it can only work with 2 sticks of memory out of 4!!
please see below the spec off speccy

Motherboard
Manufacturer Acer
Model F690GVM (Socket AM2 )
Version R02-A3S1
Chipset Vendor ATI
Chipset Model RS690/RS690M
Chipset Revision 00
Southbridge Vendor ATI
Southbridge Model SB600
Southbridge Revision 00
System Temperature 40 °C
BIOS
Brand Phoenix Technologies, LTD
Version R02-A3S1
Date 04/12/2007

is there an updated / modded bios available for my board? as i only have very minimal adjustment and nothing to do with memory!!
Kindest Regards
Danny