Also, I started adding the temp to the log when a unit throttles...
I'm thinking about adding code with slows the unit a bit as it reaches it's individual throttle temp. Like waiting 500ms before sending new work or something. Maybe. Dunno.
When my 2nd FPGA "died" in my BFL I did exactly this.
The result was useless in my case.
Adjusting it up and down (I used a getenv() to set it) appeared to make no difference at all.
(I set it to delay getenv() ms before sending new work - I tried from 100 up to about 1000)
I got the impression that the idle time was doing more bad than good
Though the death was probably something else in it crapping out since:
In my case the final fix was stupid anyway
I installed the 880 bitstream ... and it's been fine ... 2 weeks and counting ...
tl;dr story follows
I got it 4-May, but working OK from 5-May then got problems 11-Jul ... as the weather got colder ... it started to throttle and fail
(It's now the coldest part of winter here)
Then it would only mine on one FPGA.
I'd never touched the firmware coz that meant moving the stupid thing to my kids windows computer and plugging it in there to use the POS EasyMiner program.
So I did this (moved it upstairs to me instead of down in my cold basement garage) and EasyMiner said it was no good (running a test) ... but cgminer would still mine on one FPGA.
I did find a few times that if I pulled the power on it completely it would start up mining normally at 825MH/s for a while and in one case this lasted 2 days (21-Jul to 23-Jul)
After being annoyed at it for 2 weeks (code changes, power cycles etc) I decided to try kill it by putting in the 880 bitstream (26-Jul)
(sending from Aus->USA is not a cheap thing to do, so while it still partially worked I didn't want to do that)
With the 880 bitstream it's been fine ever since, upstairs here next to me, under a chair, reporting 10C higher
(air coming out is only slightly warm, not hot)
My BFL is the version with the new heatsink but only 1 fan on top so not exceptionally loud
Yeah my opinion of the throttling hardware/design is ... not good