Asus EeePC 1201HE AHCI + adding memory slot

[latr]

I found AHCI unlock for EeePC 1201N, but nothing to 1201HE. Also I look at bios ROM with AMIBCP, but dont find any AHCI settings (or any other hidden settings). Is it possible to enable AHCI? Is it supported by hardware?

Also, there are two DDR2 SODIMM pads on motherboard, but only one soldered. I soldered second connector and try it - work well, when only one memory module connected (independently in which slot installed). If two same modules connected - it shows only one module and use only half of memory (when two 2GB modules installed it see only 2GB of memory instead of 4GB). If I install two different modules - laptop dont boot, just black screen while power led enabled. Unfortunately, this laptop havent speaker, so I cant get POST error. I think this can be because two same ram modules have same configuration address, but I dont know definitely how its work and this it just assumption. Can this be software limitation, or I should seek problem in hardware? Can I read post codes from this motherboard?

PS When I dismantled laptop I saw unused connector with silkscreen label "debug_con". Is there any information about this?

Thanks.