RE: The "Y" cables.
kfc actually got it right on the 28nm Oct. PC boards.
There was a place on the PCB to install another power connector.
Top left in the pic linked below.
http://www.toboc.com/images/tradeleads/453658_hr.jpg
When kfc discovered they were in over their head understanding how to operate the General Electric DC/DC converters in pairs, and ALSO changed to Ericsson, they removed the option from the PCB to save the cost of a connector, 8 drill holes, and 6 power vias. They abandoned and removed a better solution than the "Y" cables.
On the 28nm product this almost makes sense, on the 20nm product they can't claim ignorance because they themselves used to have a better solution.
They eventually spent on just the shipping for the "Y" cables many times what the PCB solution provided, even if they got the "Y" cables for free.
BTW, kfc had the exact same issues with the Ericsson DC/DC converters, but they needed a scapegoat because of FIRE, and a local manufacturer(Ericsson) was willing to ride in and save the day. The same problen GE and/or Ericsson engineers solved in kfc's firmware could just have easily been applied to the GE part. Recall they announced that they "flew in" a GE engineer when they were in FIRE damage control mode.
And they did make changes in the firmware for existing GE product.
Disclaimer: I have a biased negative opinion of Ericsson that has more to do with assholes in the US distribution chain(Mark Oswald of Ericsson in particular) than I have issues with the quality of the product. Both manufacturers make parts that work equally with kfc's ASICs.
kfc's ignorant DC/DC converter decisions are also connected with their other huge blunder, the 5 cubes instead of 4 idiocy.
If they had added 2 DC/DC converters to each ASIC PCB they could have avoided needing 5 cubes.
They could have at the same time re-added a power connector and split the 12V rail on the PCB in 1/2 IMPROVING SAFETY!!!
The whole issue with some split rail PSU's would have been eliminated.
You can't run 1 die on 2.5 DC/DC converters but you can run 2 die on 5 converters!
They needed 25% more(than planned) rare ASICs to accomplish this.
This is also why I have speculated that 1 delayed delivery ASIC costs way way way less than 8 DC/DC converters.
They must have known they were burning the bridge to their customers at the same time.
Keep in mind, they were also 'customers' and delayed filling their data center and ended up with 20%less hashing power per ASIC also.
They poured sand in the astroglide very early and often.
Frugal to a FAULT. I hope they live long 'interesting' lives and the Black Hole investors take them to the cleaners if possible.
YMMV
kfc actually got it right on the 28nm Oct. PC boards.
There was a place on the PCB to install another power connector.
Top left in the pic linked below.
http://www.toboc.com/images/tradeleads/453658_hr.jpg
When kfc discovered they were in over their head understanding how to operate the General Electric DC/DC converters in pairs, and ALSO changed to Ericsson, they removed the option from the PCB to save the cost of a connector, 8 drill holes, and 6 power vias. They abandoned and removed a better solution than the "Y" cables.
On the 28nm product this almost makes sense, on the 20nm product they can't claim ignorance because they themselves used to have a better solution.
They eventually spent on just the shipping for the "Y" cables many times what the PCB solution provided, even if they got the "Y" cables for free.
BTW, kfc had the exact same issues with the Ericsson DC/DC converters, but they needed a scapegoat because of FIRE, and a local manufacturer(Ericsson) was willing to ride in and save the day. The same problen GE and/or Ericsson engineers solved in kfc's firmware could just have easily been applied to the GE part. Recall they announced that they "flew in" a GE engineer when they were in FIRE damage control mode.
And they did make changes in the firmware for existing GE product.
Disclaimer: I have a biased negative opinion of Ericsson that has more to do with assholes in the US distribution chain(Mark Oswald of Ericsson in particular) than I have issues with the quality of the product. Both manufacturers make parts that work equally with kfc's ASICs.
kfc's ignorant DC/DC converter decisions are also connected with their other huge blunder, the 5 cubes instead of 4 idiocy.
If they had added 2 DC/DC converters to each ASIC PCB they could have avoided needing 5 cubes.
They could have at the same time re-added a power connector and split the 12V rail on the PCB in 1/2 IMPROVING SAFETY!!!
The whole issue with some split rail PSU's would have been eliminated.
You can't run 1 die on 2.5 DC/DC converters but you can run 2 die on 5 converters!
They needed 25% more(than planned) rare ASICs to accomplish this.
This is also why I have speculated that 1 delayed delivery ASIC costs way way way less than 8 DC/DC converters.
They must have known they were burning the bridge to their customers at the same time.
Keep in mind, they were also 'customers' and delayed filling their data center and ended up with 20%less hashing power per ASIC also.
They poured sand in the astroglide very early and often.
Frugal to a FAULT. I hope they live long 'interesting' lives and the Black Hole investors take them to the cleaners if possible.
YMMV