Strange pc problem bios mod request

[savvyx1]

Hi, so as the title suggest I am encountering one of the weirdest problem in all my 10 years of pc use, my friend has given me this system for repair saying he wanted to try a new processor ( Intel Xeon E5420) that came already modded to support his motherboard (Acer FG43D or after more research also called Veriton X480G) which has an LGA775 socket and chipset g43 which should be compatible with the modded CPU, but here comes the tricky part the motherboard should also be compatible with Intel Core2Duo E8400 and it dosen't work either, but suprisingly using an Intel Pentium E2220  dose the job, I tried to upgrade the bios to the latest verion but neither the modded xeon or the core2duo worked, then I realised the motherboard actually support only Duble-Sided DDR3 800/1066 MHz non-ECC and I was using 4GB Hynix DDR3 1600MHz PC3-12800 which from my knowledge is single-sided memory, thus the reason for cpu incompatibility, now I wounder would be possible to modifiy the bios in any way so it will make the single-sided memory work with the xeon cpu? The system he is using at the moment is running:                                                                                              Operating System Windows 10 Pro 64-bit
CPU Intel Pentium E2220 @ 2.40GHz 
RAM 4 GB Single-Channel DDR3 
Motherboard: Acer FG43D 
Graphics SAMSUNG (1360x768@60Hz) 1023MB NVIDIA GeForce GT 610 
Storage 149GB Western Digital WDC WD1600AAJS-60PSA0