FIX Games Work in SD+CDDA and NOT in IDE+CDDA

[gng4]

something I really don't understand, may need help from expert advice...

my last bios mod g1ata HDD 80gb system: region japan (I believe), piggyback bios nogdrom, DS RC4 played well and no problems with games: Radirgy, Triggerheart Excelica, Space Channel 5 Part 2 (those reported not working by dragoncity)

now the system after playing Sturmwind failed, seemed like overheated: when switched on Dreamshell opening animation flickered with slow motion (music normal so both not in sync anymore), after animation ended then freezed, no idea how to fix...[attached clip to show the problem, any ideas on how to fix are welcome]

my second system is the same as first, but I believe it was a PAL board and used region changer mod, I used region changer 1.85 and found region - Japan, broadcast - NTSC, Language - English, I made the region changer mod and changed the Language to Japan

this system before and after the region changer mod did not work with the games (as above) that worked in my first system, I just don't understand...

are there other differences between PAL board and Japanese board which region changer cannot change, or some codes which are presented in Japanese board but not in PAL board to make Dreamshell work with games in one system but not the other?