Also make ur gnd wire shorter/thicker. Add solder to those bios points, cauz what happens is, is that when your chip is transmitting and receiving data its going though those bios points quickly (electrons = data) if there isnt a good connection the data (electrons) cant get though easy and that causes heat. Use 60/40 solder and make good contact between all your solder points if it still happens then try putting your ps2 in a cold area (basement) and play it if it still is happening look at ur chip and look for bad solder points, if you can get a hold of a good disecting microscope you can see all the connections very clearly.
V7 PS2, HDD, MagicV, Collecting Dust
V5 PS2, MagicV, Collecting Dust
PSP 1.5, devhook loader, Collecting Dust
PS3 1.32, 60gb HDD, YDL5.0