On the watts or mh/s?

Did you expect a clear answer?

I really wonder what it is you perceive as being harsh criticism.

Mining on CPU or GPU was a hobby activity.  I've got this gear for other purposes, so why not harvest a few bitcoins as well?

Buying purpose built FPGAs is a business.  What I posted was my analysis of the business proposition ET made.  It's a non-starter for me for the reasons I shared.  I posted in the hope of learning where my analysis was incorrect, or possibly influencing ET to choose a compensation model that I could participate in.  So far, no luck on either, but it appears that he hasn't read, or digested my feedback yet, so I will hold back on my input on what might make a workable model.

I also wonder what was so vexing to you that it lead to your only substantial post ever on this board.

You might find that a bit difficult to do without the private key.

This is correct.

Busted!

This concern is valid.  The ztek boards do not supply enough power. This is why I have been encouraging designers to budget for more than 8A.




This is misleading; you are fretting about device damage but basing your calculations on the error-free-operation parameters instead of the device-damage parameters.

Xilinx guarantees their chips can tolerate operating junction temperatures up to 125°C (see page 2 of DS162) without damage, for all temperature grades (they're manufactured identically, then sorted by testing).  Using your thermal constants, this means that a CSG484 can handle 26A of current (!) and an FGG484 can handle 20A of current without being damaged (though, of course, the error rate will be 100%).  Anyways, that's plenty of current, even for bitfury.

For each temperature grade Xilinx publishes another, lower, limit above which they will not guarantee perfectly error-free operation (85°C for the C-grade devices).  People using FPGAs for bitcoin mining are already far beyond the "guaranteed perfectly error-free" region on other axes like clock frequency.

According to Austin Lessea (of comp.arch.fpga fame; a Principal Engineer at Xilinx) "the device is incredibly robust as far as junction temperature is concerned, and it would have to be at 125C and hotter for a long period to cause damage."



The 8A power supply on your board will go into overcurrent or thermal shutdown long before the FPGA is able to damage itself by self-heating.

To avert any possible FUD I'll put my money where my mouth is: 100 BTC bounty to anybody who sends me source code for a bitstream that causes permanent heat damage to my ztek board, with heatsink installed and fan running.  No unusual I/O pin usage allowed, and the design has to pass Xilinx DRC.  If you think there's a risk step right up and claim the bounty!

Edit: created a separate thread for the bounty.

awesome updates, m8. Has anyone submitted the neccesary enterpoint info and/or sent you a unit to test your bitstream on theirs?

If not, any plans to work on an enterpoint stream?

Sorry, couldn't help throwing in a little sarcasm ... I'd think he expects mining software to be updated for free to support this new requirement ...

I'd also add that I can't see that happening with some of them at least.
Seriously? Update the bitstream if the servers don't respond? Wow I can see all sorts of problems with that
Then deciding to switch the bitstream back ...
though I guess if enough time and effort was spent predicting and dealing with possible issues ... ...

Those who use what I'm sure anyone will agree is probably the most advanced miner (cgminer) resolve server failure easily.
They have multiple pools.

In this case you can't do that the way it works at the moment, since, the failover occurs even during normal mining (unless you tell it to not do that and lose work) since servers aren't always 100% perfect ... for anyone ... ... ...

I'm only hashing at 1.9GH/s at the moment, but of the 50k getworks on my 2 rigs (running 4.5 days) 1.5k were to the backup pools.
Shares, of course, are lower but even there, of the 179k shares, 200 of them were the backup pools (so only 0.1%)
However, my internet has been 100% stable over the past week (it usually is anyway) and the main pool has been 100% stable also.

When the stability level drops, cgminer does it's best using all the pools as much as possible (and often at the same time) to keep the devices hashing at full speed.

This is, of course, talking about a solution that is definitely not elegant but certainly does rely on being able to define a clear line between your servers working 100% and not working 100% (which I'd wonder how clear that line would be and how easy it would be to detect without losing a lot of work)