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.
Thanks for the info. It looks like it's more work to do. Loosing 3% hashrate for voltage drops would be sad.
50mv drop is horrible!
adding a couple thick wires from the output of the VR to the last chips should help a lot. although the problem could be a return path issue. I dont have my unit in front of me at the moment. I assume the bottom layer is Ground and the top is VCC? There may be an issue with the ground vias/pins not being able to handle the current.