Havenīt noticed that IOH.. try VTT same as before, and IOH on default level.. (at 200 BCLK I havenīt noticed any improvement with increasing IOH voltage.. used that on 210+ BCLK). Btw. I need +200mV VTT for having it stable, you have D0 which should be lower, but maybe not too much.. try those +100mV you tried and maybe more (up to +200mV). 1.3V means you probably run on default voltage.. try increase of +50mV. Which should give you 1.35V on load.. and can be more stable. But also much more hot..