That's strange. I double-checked the values that GSM uses and it seems to match the ones from my SCPH-77006... If your PS2 was older (GS revision < 1.9), then it could have been because the SYNCH values don't match. The value in these fields of these registers changed between GS revisions: SYNCH1: HBP, HFP SYNCH2: HB, HF For other video modes that were already available on older consoles, there is code for setting the right SYNCH1 and SYNCH2 values for the installed GS revision. However, mode 0x53 (576P) does not have such a thing. PS2Linux also had 2 sets of sync values, for the 2 groups of GS versions. However, since it came out before the 576P mode was added, it has no information on the 576P mode. It also has no information on why the sync values are different. Since your SCPH-50004 has revision 1.11, it should not be affected by this difference. You wrote that you could use 576P properly with your newer PS2, but was it using this same TV and cable? That's great news! It can be backported, which is why I am posting in the GSM forums. But I'm just not so willing to adopt yet another project.