PS2 Crashing

I've got myself here an old PS2 that hasn't found much use cause of my newer one. It's a v4 USA with Magic3.1 which initially worked fine.

I try it today and games are crashing at various points like GT3 crashes going into any screen after the main screen, Midnight Club 2 crashes on intro movie, some games lock up randomly while others don't start at all..

I've checked all the points for possible cold solder joints, continuity, etc.. everything looks fine.. I even took out the chip and it still seems to happen. One noticable difference is when starting up, the SCEA screen has noticable black blocks which ruins the startup font. I've attached a screen cap to illustrate what I see. I've done almost everything and can't find what the problem is.. any guesses?

Versions 4's are known for having 'issues'. I would completely re-do the install (remove all wires, clean up everything, start over), clean the laser lens and optics, check the pot's, then give it a go.

take the chip out and cleanup the board. Remove excess solder and reheat the solder on the 22 soldering points (make sure no cold connections)

I definately think now this v4 is one of those with "issues". Before any no swap chip, it did have a swap mod, Neo2.2 to be exact that didn't work most of the time. Taking out the mod it worked fine again.

When I put in the Magic 3.1 in it worked fine for as long as I can remember then all of a sudden this happens. I've completely removed the chip and cleaned all the installation points and it still doesn't work in its original state. I didn't look at the laser cause I don't suspect it to be the problem since on boot up when the SCEA words come up its still garbled like the attachment in my original post.

The only things left to try are to change the chip which I doubt is the problem, and chage the laser, again the same reasoning. My only thought on this would be the BIOS since it's noticable on startup with/without a disc in it but the BIOS looks perfect with no dust or anything.

I've gone one step further now which was swapping out the motherboard for another one into a known good unit and the problem persists so I know it's isolated to the motherboard somewhere. Any guesses as to which component would cause this?