Have you tried to add caps very close to GPU or VRAM to existing MLCCs?
From my experience doubleing the big solid caps gives less profit.
I may try adding some 2.5v solid caps on the MLC's behind the core, so long as i can still figure out a way to mount the GPU to a pot.
*At this point Im just trying to stabilize the GPUv a bit more.. this PCB is too tight for me to add 2ndary inductors, or swap the stock ones .. ...I feel thats what it really needs.
@ bass- the 4890 layout is similar tot he 5870.. the 1x I did for Patch was really good.. pics below of added caps. Both SMD/MLCC & solid caps used.