Topic: Question to multi-BFL Single miners: temperature and throttling issues - page 3. (Read 7063 times)

There are several factors involved, but the bottom line is that if it throttles in an ambient temperature of 72 degrees Fahrenheit than we'll gladly replace the unit.  If you're just curious as to the inner workings and want to know what factors are in play, please contact me in private and I'll do my best to answer your questions.

Regards,
BFL

I'm not a guy who cries wolf easily and only discovered that one of my Singles is throttling down frequently after zefir's post.
I am, however, in the process of phasing out all GPU rigs (in fact, just a few minutes ago I turned off my 2nd GPU rig for good, leaving only one rig running now).

Even with only one GPU rig running as we speak, this one "problem Single" is throttling down to about 500 MH/s quite frequently, right now, for instance, to 544 MH/s, and I may request a replacement unit at some point in time, after turning off the final GPU rig and after measuring the room temperature.

BTW, CGminer shows the "problem Single's" temperature at only 50 or 51 degrees Celsius, while the other good unit one foot away from it shows 64 degrees and mines along happily. So it seems to me that this "problem Single" may actually be throttling unnecessarily, or overly aggressively. By any chance, is there a trim pot inside by means of which an END USER could adjust the throttling threshold? Or is the throttling threshold error based like in the ZTEX design?

Just now I looked at the CGminer panel - the "problem Single" was at 823 MH/s and 53 degrees, whereupon it started throttling again. I don't deem 53 degrees a dangerous chip temperature and thus I'm really wondering what's going on here...

Inspector, as I read your post I was preparing a response to ask you why you haven't contacted us about the issue...  until I realized you were running it in a hot ambient temperature.  Understood.

Actually, I place all my singles on their pretty face, cables sticking out on top.
This should allow for maximum airflow.

Yeah, in fact one of the fans I just ordered is a 103 cfm, 61 dBA Delta fan. 
It's 50mm thick, so maybe you're using that as well.
SVC.com has them on sale for a mere $10 - regular price is $65.

Be men and add some REAL fans, pussies! http://vimeo.com/41028028

I have found that elevating the unit about 1" so the bottom fan can work more efficiently gives me about 5 degrees cooler temps.  Maybe give that a try.

In think you are right, after all.

Upon closer examination, one of my Singles (the first Rev. 3 Single with an external fan attached) also seems to blink.
See, when BFL wrote "will blink" I was expecting it to blink continuously, but that's not what it does.
It blinks for a few seconds as it throttles down to some 530 MH/s, and then, as it gradually increases its frequency again (probably in a ZTEX-like fashion) until it reaches 820 MH/s again, it does not blink, until the throttling game begins again.

Placing a 133 cfm fan on top of the unit to aid the internal fan in sucking hot air out did not help at all. Neither did positioning the 133 cfm fan at one of the side vents of the throttling-afflicted Single.

However, placing the 133 cfm fan at the BOTTOM of the Single, aiding the Single's external bottom fan, seems to have done the trick for me and thus I can recommend swapping the bottom fan of the Single for a higher-cfm model.

Edit:    No, it still throttles. Took it quite some time; I was seeing 825 MH/s for a long time, but it's at 591 right now, already on the upslope again. 754 now. Upslope. Nevertheless, I have ordered a few fans from Silicon Valley Compucycle, all of them 65 cfm and above, and will probably open up this Single and swap out the fans. Admittedly, my mining environment is quite extreme as the central AC does not manage to replace enough hot air with cool air.

There are 2 places where some lights blink: On the front panel is the power light, and also the one that indicates throttling. Inside on the right side, there is another pair that pulse whenever a nonce is sent to the host and other indications. The front panel one is the one to worry about, and it should be fine if your ambient is less than 72 degrees F or about 21 degrees C.

Hi BFL (Sonny?),

thanks for the advice.

I did not since there is no issue. The devices are just doing a great job, congrats. Even the throttling one is within performance specs (832-10%), plus it is comforting to see that the devices take care themselves to not go up in flames.

I was just hoping that someone did a better job than your engineers in cooling it down (no offense, many Bitcoiners do better jobs than GPU manufacturers ) and max it out. But again, they are just running fine as is.

Nevertheless, you could maybe clarify the LED states here or at the product page (if not already done elsewhere).


Thanks

Hi zefir, please write office @ butterflylabs.com for assistance if needed.

Kind regards,
BFL

Yeah, I guess I'm ahead of time. Assumed people already started tweaking it to push it to the max (like done with GPUs), but I guess most are just happy with it as a plug-and-mine device.

As for the LED blinking, I'm pretty sure I read somewhere that a blinking front LED indicates throttling. Plus in my setup it is only the device with the lower hash rate that blinks, which I take as strong indication for throttling. What you maybe mean is the internal LED at the right side that goes off every ~5s for a short moment. I'd guess this is when the work is done and it stops for a moment to deliver shares and get fed with new work.

Also, with now running for 72h continuously I'd exclude variance as a cause for 4 devices being exactly at 810 and the fifth at 65 less. I'm pretty noob when it comes to HW, but I'm tempted to disassemble (and pretty sure brick) it to see what's wrong.

I think that all of your Singles are fine and the small temperature variations that you see are just that, random variations.
I also think that a brief blink every 3 minutes is not an indication of throttling, but rather an indication that the device has found a match or that it is being provided with a new work unit.

Hi BFL miners,

received my Singles recently and wanted to hear if someone had similar issues with throttling.

I got 5 of them that I put mining right away (i.e. without opening the housing ). They seem to be all Rev.3 ones with no additional bottom fan with the only noticeable difference being one has a passive copper heat sink at the PCB-bottom, while the other 4 have blue heat sinks with fans.

BFL-Engineer already wrote that thermal design is a challenge and every board has individual characteristics. Though, I found it really strange that two of them are blowing 'cold' air out of their case, while the other three exhaust is almost hot air. Since all boards are operating under the same environmental, I'd expect all to get relatively equally hot.

That's the subjective side. The objective values running the setup for 48h with cgminer are:

No.	av. Temp °C	av. MH/s
1	63	810
2	54	810
3	56	810
4	60	757
5	61	809

Device 4 is throttling (LED is blinking every ~3 minutes), but it is not the device with the passive heat-sink (that's device 3). My interpretation of the values (as far as I can trust cgminer measures) is that devices 1 and 5 (those with the 'cold' exhaust) have sub-optimal temperature-conductivity to the heat-pipe. Device 4 is worse in that and hits the throttling threshold (~65°C) resulting in a varying temperature averaging down to 60°C. Does this sound reasonable?

Did you had similar issues with multiple boards varying similarly? Anyone already tried to dismantle the heat-pipe and re-apply thermal grease or pads to improve stability?

Generally, the setup is fine and delivers exactly 4GH/s. But while the relative loss through throttling is small, anyone would RMA his GPU delivering 50MH/s less its nominal rate. Also, improving temp-conductivity might not only increase hash rate but also help durability.


Any thoughts or hints? Thanks.