I have found a particular problem whit Linux and 4Gb memory whit this motherboard, the GA-MA78GPM-DS2H rev1.0 , similar problems I had whit a rev1.0&1.1 GA-MA78GM-S2H I had before it as well. (I managed to fry those two GA-MA78GM-S2H and as the third replacement I talked myself the better more expensive GA-MA78GPM-DS2H in return for free as replacement whit reason I should not get more fried boards whit that one instead )
I have a Phenom X4 9750 2.4Ghz(95W) and 2x2Gb corsairs XMS2 DDR2 800Mhz memory. Having the 4Gb installed shows no problems but I get problems when I want to try to use the full 4Gb memory.
There is a option in the Bios which decides if it should use below 4G or above. memory re-mapping or something like that.
When it's set to use below 4G I can't use the full 4Gb off memory and limited to something in the 3Gb, any linux distribution, memtest etc work all good whit this below 4Gb memory usage, but I want to use all off my memory so I try to set it to use above 4G re-mapping but this is a hell for anything but windows... only windows will work whit above 4G, memtest or any linux based thing will give crap in return and will be unusable. This GA-MA78GPM-DS2H works a little better than the GA-MA78GM-S2H I had earlier whit memtest working atleast whit above 4G choosen but the Linux stuff is still a no go in totality.
Whit above 4G anything to do whit linux kernels etc is full stop and freeze in various diffrent ways. The most colorfull ways was whit the GA-MA78GM-S2H giving some real nice abstract boxes of "Tv ant wars" in colour stills when trying to boot a linux dist. (as soon as I tried to start anything whit the linux stuff). (grub works all good though) The newer GA-MA78GPM-DS2H I get farther inside in the booting and such. I get as far as to login but as it should load the desktop it freezes whit the X cursor and nothing responds. You can't even start the live-cd's whit above 4G going on any off the various Ubuntu distributions I had burned. I had some seatool hdd thing that used some other linux kernel stuff and that doesn't work either whit the above 4G setting.
I reckon it's some bad coding in the works in the BIOS for the Gigabyte motherboards?
You guys know off anything?