The class code indicates a RAM test write failure, but the chip identification code does not indicate chip 3. That's an error of interpretation. The chip identification codes are bit based, so the values are 0001, 0002, 0004, 0008 etc. So unless 0003 means 0001 + 0002 failed (which is unlikely I think in such a simple RAM test) it instead seems to indicate an alternative problem, or a side-effect of your screen problems. But remember that the screen is memory mapped, so screen artifacts could also indicate bad RAM.

Edit: actually, after searching a bit I have seen some reference to multiple failures being reported in the chip identification code, so perhaps this is indeed indicating F5 and F6 both failed the write test. But nevertheless I concur with Mac128 that this does not necessarily imply chip failure, and it is worth investigating alternative and easier to repair causes as far as possible first.