I measure my board with my 100MHz oscilloscope with 1.3V mod and did not see noise on power lines. I check it now after over 10 days mining.
About drop:
Standby: 1.298V
395MHz:
1.278 on coil VR and nearest capacitor  
1.268  first two chip
1.228 last chip.

I solder  silver-plated wire 0,8mm across  one board and check how its help.