I was just digging thru my stuff to find my 475's and a bunch of VRAM to play with when I realised that I'd already given them away! To a good home of course, but now I need to get me another 475 - I love those machines 
I don't remember having any VRAM type problems coz those Macs are fairly bullet proof. Maybe I was lucky with the VRAM speeds because I certainly never checked the label!!! Given that you're testing on two Mac's and getting the same results on both suggests to me that there's something up with your VRAM (ha! I trust a 475 board more than a stick of VRAM aquired out of singapore
) Possibly you could check your VRAM in another Mac which has only one VRAM slot (like a LCII), or post your stick to someone else to test.
I don't remember having any VRAM type problems coz those Macs are fairly bullet proof. Maybe I was lucky with the VRAM speeds because I certainly never checked the label!!! Given that you're testing on two Mac's and getting the same results on both suggests to me that there's something up with your VRAM (ha! I trust a 475 board more than a stick of VRAM aquired out of singapore
) Possibly you could check your VRAM in another Mac which has only one VRAM slot (like a LCII), or post your stick to someone else to test.