So it turns up its not really hard to do....
Here are ztex schematics http://www.ztex.de/downloads/usb-fpga-1.15x.pdf
We need to fiddle with R12 and/or R13 to bump the voltage.
Formula to get the voltage is 0.8*(1+R12/R13)
On schema or (high res pic1
, high res pic2
) we can see:
R13 = 2k4
R12 = 1K3 , pcb print says 1K2 in reality R12 is 1370 ohm, which means (by the formula) default voltage should be 1.256V
VCCINT can be checked here:
and it showed me 1.264V on my multimeter by default.
I decided to go with 50k parallel multi-turn trimmer that would result at 2290ohm instead 2400 at 50k. That should bring us to about 1.28V.
I know its ugly but it works (i redid some of the soldering after seeing this pic). Also it doest matter if the R12 and R13 are shorted because they are anyway via pcb.
The readout on the red and black wire straight after - 1.286V.
This increased my stable hashrate from 216 to 220, ztex miner did try to push higher but it went down to 220.
Time to crank it up, some sources say ztex tested up to 1.4v and for bitfury we know he runs 1.5v in OC mode, Xilinx says it's okay to go up to 1.32v.
Also, I am not responsible for your fried boards.
Results w latest ztex sw/fw, 0% invalid:
1.264V 216mhash //default
1.320v 232mhash //Xilinx approved
1.410v 248mhash // tested with extensive cooling,.. this is the max that ztex bitstream can go.