I got 8400c34 to run 2.5hrs of VST/VT3 in 20second iterations before error, RxDfe off. Becareful24 told me that's as good as it gets without debug menu.
SA 1.20, VDD2 1.425, TX 1.225, VDDQ_mem 1.42, VDD_mem 1.60, ParkDQS 60, CMD/CTL Drive Strength Up/Dn 2D [Disabled], CMD CTL CLK Slew Rate...