Quote from: elasticband on February 16, 2014, 11:13:25 AM

Quote from: crashoveride54902 on February 16, 2014, 12:47:42 AM

Quote from: elasticband on February 13, 2014, 11:20:33 AM

DO NOT ATTEMPT THIS

Three attempts with a single 8vrm board for tests and each time i got the same result, a CRAZY buzzing noise from each VRM.

I have had this before from a board that got RMA'ed.

edit: few minutes after powering off i hear this clicking noise, like a switch being flicked. I also heard this on the faulty 4vrm board.

just did this and i can confirm it works and i hear no funny noises...i used same volts as he did -0.0527

5-8c drop in vrm temp, i'm rocking 2 241 n 2 271 now...temps all below 50c and the 8vrms mods are lower temp then 4vrms n oc'd more man i wish i had more 8vrm mods...

730gh/s 10200 WU with .31 hw errors...guess i'll wait for 24hr avg to see if it holds yay!!

just tried it with a second 8VRM jupiter, same result, crazy buzzing/hissing noise from all boards.

I have inspected what the November firmware has actually changed.

What I can see it has changed a value in one of the registers in the VRMs. It has set the "ON" bit in the OPERATIONS register,changing what conditions are needed to turn the VRMs on.
This change will be permanent even if rebooted or power-cycled. It can be changed using i2c commands:

Turn all VRMs on:

#!/bin/sh
# Stop SPI poller
i2cset -y 2 0x71 2 0

for b in 3 4 5 6 7 8 ; do
for d in 0 1 2 3 4 5 6 7 ; do
i2cset -y $b 0x1$d 1 0x80 >/dev/null 2>&1
done
done

Restore to factory settings:

#!/bin/sh
# Stop SPI poller
i2cset -y 2 0x71 2 0

for b in 3 4 5 6 7 8 ; do
for d in 0 1 2 3 4 5 6 7 ; do
i2cset -y $b 0x1$d 1 0x0 >/dev/null 2>&1
done
done

I suggest stopping cgminer before doing this to limit the power when the operation is done.

Reading the datasheet for the VRMs I can see that when using them in pairs (as we do when all are turned on) there are some requirements on how they should be turned on. This method does not do that!

I have heard that hizzing sound as well. Some boards do that. They did that on 0.90 firmware too. No idea why.

I do not know if this is safe or not, it might be unsafe and burn your boards.