Question to multi-BFL Single miners: temperature and throttling issues

[twmz]

I also have a unit that is less tolerant of higher than supported ambient temperatures.  The room is 75 instead of 72 and one of my singles throttles regularly while the other never does. Until I can try EasyMiner's tuning, I have been trying to improve airflow in hopes that I can reduce throttling as much as possible. 

To that end, last night I removed the U-shaped cover piece to the unit that was throttling (the piece that wraps around the sides and the front) to expose the heatsinks and fans.   With that piece removed, the device stopped throttling in the 75 degree ambient temperature.  Note, I do have a room fan pointed at the table these are sitting on and so my assumption is that with the case removed, that room fan is providing enough additional circulation to offset the increased ambient temperature.

So it's something you might want to try.  Note, to remove this easily, you only want to remove the 4 small screws on the sides (2 per side).  The "back" is the side with the USB and power connections.  There are 4 small screws there you want to leave alone.

Side note: I hope EasyMiner's speed adjustments will be persisted in nvram or something?  So, if it is a windows-only app, I can make the adjustment and then move the Single back to my linux rig?  If not, please make the protocol for adjusting the speed public so that the cgminer developers can add this feature directly.

[zefir]

I also have a unit that is less tolerant of higher than supported ambient temperatures.  The room is 75 instead of 72 and one of my singles throttles regularly while the other never does. Until I can try EasyMiner's tuning, I have been trying to improve airflow in hopes that I can reduce throttling as much as possible. 

To that end, last night I removed the U-shaped cover piece to the unit that was throttling (the piece that wraps around the sides and the front) to expose the heatsinks and fans.   With that piece removed, the device stopped throttling in the 75 degree ambient temperature.  Note, I do have a room fan pointed at the table these are sitting on and so my assumption is that with the case removed, that room fan is providing enough additional circulation to offset the increased ambient temperature.

So it's something you might want to try.  Note, to remove this easily, you only want to remove the 4 small screws on the sides (2 per side).  The "back" is the side with the USB and power connections.  There are 4 small screws there you want to leave alone.

Side note: I hope EasyMiner's speed adjustments will be persisted in nvram or something?  So, if it is a windows-only app, I can make the adjustment and then move the Single back to my linux rig?  If not, please make the protocol for adjusting the speed public so that the cgminer developers can add this feature directly.

I already tried dismantling the case of the throttling one along with what was suggested by the other users. Nothing did really help, i.e. the time between the start of mining and first throttling varies with the attempts, but once it starts it does it with same frequency, resulting in a long-term hashrate of 710-730MH/s.

The best I got so far was a result of pure monkey testing: I turned the upper fan and put it back into the housing. Instead of blowing out the heat-pipe's hot air to the top, it now sucks the fresh air from there and pushes it through the heat-pipe and the VRMs to the side exhausts. It's just a trial-and-error result and people familiar with thermal design might argue this is stupid, but it works for me.

[Shadow383]

The best I got so far was a result of pure monkey testing: I turned the upper fan and put it back into the housing. Instead of blowing out the heat-pipe's hot air to the top, it now sucks the fresh air from there and pushes it through the heat-pipe and the VRMs to the side exhausts. It's just a trial-and-error result and people familiar with thermal design might argue this is stupid, but it works for me.

Makes sense, you'll generally improve thermal performance by having the fans "push" airflow rather than pull, as the flow is much more turbulent, increasing the amount of heat leeched away from the surface due to the increase in boundary-layer vorticity.

[kano]

Got mine today (from someone else on the forum) it's with the single fan/new heat sink (whatever version that means)

I plugged it in to my desktop (linux) and 830Mh/s for the 41 seconds I ran it.
Thought this is nice - performing as expected ... time to take it down to the (underground basement) garage where my rig is
FYI here in Sydney Aus today it's 20°C where I am - my garage is cooler (it's autumn, winter in 1 month)

Took a while to work out how to get xubuntu 10.04 to recognise the BFL at all.
(luke-jr came up with the answer - anyone wondering: "sudo modprobe ftdi_sio vendor=0x0403 product=0x6014")

After a few minutes running ... throttling.
This is odd - coz the temp (reported from cgminer) was below 50°C - always.
Throttling down to crappy hash rates 680MH/s ... for an extended time.
On exit with that:
 Runtime: 0 hrs : 34 mins : 1 secs
 BFL0  47.3C         | (5s):708.0 (avg):696.9 Mh/s | A:275 R:4 HW:0 U:8.1/m

Yeah that sux badly.

So I brought it back upstairs to run it in it's own cgminer and find its ... slightly better ...
But WTF?
It's reporting it's temperature always above 50°C now even though it's getting a slightly better average MH/s
Current stats:
 Runtime ~70 minutes
 BFL 0:  52.7C         | 733.6/743.0Mh/s | A:655 R:6 HW:0 U: 9.40/m

I'd guess this is going to be some 'return it' and get a replacement .......
As for their EasyMiner program - yeah I'm gonna expect some details of the extra protocol from them to see if I can fix this thing myself.

I bought this for a few reasons:
1) cgminer (obvious - I wrote some of it)
2) I only had to pay BTC to the person I got it from
3) I got it in LESS than a week after I discussed buying it from them

I guess it's time to try email ... unless someone else can supply the extra protocol commands
(or has a copy of EasyMiner to watch what it sends to the BFL)

Edit: oh and the front led supposed to flash? Never seen it do it (except at power on for a short while)

[Inspector 2211]

The front LED flashes only for a few moments when the Single reduces its [clock speed?] hash rate, but not while it slowly increases its speed again.
Btw., my throttling issue seems to have been resolved by lowering the room temperature. I lowered it by turning off a GPU mining rig.

[zefir]

My throttling device's front LED toggles for around two seconds every 3 minutes or so. Whether this is the down-clock phase or the time where it stops mining I don't know, but from the effective hashrate it is more the down-clock (2/180 idle cycle time won't make up for the 15% hashrate drop I have).

My attempts to circumvent throttling have been futile so far. Along with the suggestions made by other users in this thread I let it mine outside over night at < 14°C. No matter what, the 12h+ average comes down to ~715MH/s. I'm therefore pretty sure something went wrong when the heatpipe was mounted (the other 4 devices are always at ~815, no matter what). Look at the ztex thread: people are achieving significant speed improvements with different thermal grease / heatsinks combinations or the process how they are applied. Since no one tried that for BFL Singles so far, I'm not going to brick mine trying. I'll wait for EasyMiner and if that's not fixing it, mine goes back to BFL (it is at < 832MH/s - 10%).

[rjk]

Wait, so on one instance of cgminer it is slow and on another it is faster? Is it a host system limitation of some kind? Although I doubt that. Did you check to make sure that the heatsink was firmly attached? There have been reports of it dislodging during shipping.

[zefir]

Wait, so on one instance of cgminer it is slow and on another it is faster? Is it a host system limitation of some kind? Although I doubt that. Did you check to make sure that the heatsink was firmly attached? There have been reports of it dislodging during shipping.

If you mean my setup, no. It's one cgminer instance operating 5 BFL Singles (plus 3 GPUs) with 4 of them running full speed at ~815 with no throttling and the problematic one at ~715 on average, no matter how I try to add external cooling. I'd assume the conductivity from chips to heatsink is problematic, but I'm not going to dismantle it and void warranty unless someone experienced that you can recover a throttling one by e.g. re-applying thermal grease. The heatsink is tightly fixed, BTW.

[rjk]

Wait, so on one instance of cgminer it is slow and on another it is faster? Is it a host system limitation of some kind? Although I doubt that. Did you check to make sure that the heatsink was firmly attached? There have been reports of it dislodging during shipping.

If you mean my setup, no. It's one cgminer instance operating 5 BFL Singles (plus 3 GPUs) with 4 of them running full speed at ~815 with no throttling and the problematic one at ~715 on average, no matter how I try to add external cooling. I'd assume the conductivity from chips to heatsink is problematic, but I'm not going to dismantle it and void warranty unless someone experienced that you can recover a throttling one by e.g. re-applying thermal grease. The heatsink is tightly fixed, BTW.

Sorry I meant Kano.

[kano]

Wait, so on one instance of cgminer it is slow and on another it is faster? Is it a host system limitation of some kind? Although I doubt that. Did you check to make sure that the heatsink was firmly attached? There have been reports of it dislodging during shipping.

The two hosts are in 2 'different' environments.
One is here my desktop and the other is down in the underground basement garage that is clearly cooler.

However ...
... and my overnight run shows that it is indeed exactly ambient temperature related.

So although that does sound like a loose heatsink, I'm still wondering why the temp reported is always below 55°C
(I would say below 50°C but it has now got up to 50.x°C and hovering at 49.1°C - it's now 9:45am)

Last night the weather predicted temp was 9°C and BFL running in the basement got the expected average of 815MH/s
Up to an hour before the last time I restarted cgminer (3:30am) it was still throttling
(of course during an LP is expected, but it was also throttling not during an LP)
The fact that the 5s average was pretty much always at 826MH/s before 3:30am (except during LP) suggested to me that it had indeed dropped to whatever temperature it requires to not throttle

So my guess is one of:
1) the throttling process in the BFL is brain dead/faulty in my BFL (hmm I remember saying something about that in the BFL thread - suggesting it be possible to control the throttling - since hardware isn't always perfect - a LONG time ago)
2) the temperature that cgminer gets from the BFL is unrelated to the temperature used to determine throttling
3) the ambient temperature needed for a BFL is not far above a fridge (close to 10°C) and that should be made abundantly clear

Of course 3) could simply be a loose heat sink - but then 2) would also need to be true

Edit: of course I did email BFL about this 13 hours ago so I guess I'll see what they suggest also.

[kano]

BFL (Sonny) replied with the same suggestion about it being a loose heatsink
(and a BFL replacement if it wont work properly)

Fortunately for me it seems most likely to have been some sort of "burn in" issue
since once the temperature dropped that night after midnight and it stabilised, it hasn't had any more non-LP throttling since, during the almost 2 days and nights since!
(though maybe that is also due to the temperature here being quite cold for the last two days?)

The non-stop stats for almost 1 day 19 hours has been:
817.3Mh/s (A:29504 R:331 HW:0) U:11.45/m

Sonny also said that they will be releasing their miner soon Quote: "I hope to do so within the next week" (no idea what that really means)
but made no mention of the details of the commands to control the throttling that will be in the new miner
I guess we'll just have to wait until it's released and then get the commands out of the miner
(damn annoying decision that one is)

I still have no idea if the temperature reply from sending the "ZLX" command is related to the temperate used from throttling ...

[Inaba]

Easyminer will allow you to flash different firmware.  The thinking goes that if you reduce the max speed, it will throttle less (or not at all) giving you better overall hashrate.

[Tamerz]

Been running mine since yesterday. It is warm in this room and cgminer shows the single at 69 - 70 constantly. It hasn't done any type of throttling at all and stays right around 800Mh/s.

[BFL-Engineer]

During throttle, the device does respond to temperature read, status read, etc.
A new job, however, cannot be issued, as the unit will respond with 'BUSY'.


Good Luck,

[tarrant_01]

I had a throttling single.  I opened it up and the heat sink wasn't attached properly to the board.  One of the 2 spring pins wasn't pushed down.  After securing it, I've had no more issues.  Open it up and check it out or stick something through the vent and see if you can move the heat sink.  If it moves then it needs to be secured.

[kano]

During throttle, the device does respond to temperature read, status read, etc.
A new job, however, cannot be issued, as the unit will respond with 'BUSY'.


Good Luck,

What I mean is that: if I see a temp (ZLX) of 49C is that the same number tested by the throttling firmware that decides to throttle the BFL?
So whatever the first throttling temperate is inside a BFL (when it first drops below 832MH/s), I should see (ZLX) close to that "throttling temperature" just before it decides to throttle?

[BFL-Engineer]

During throttle, the device does respond to temperature read, status read, etc.
A new job, however, cannot be issued, as the unit will respond with 'BUSY'.


Good Luck,

What I mean is that: if I see a temp (ZLX) of 49C is that the same number tested by the throttling firmware that decides to throttle the BFL?
So whatever the first throttling temperate is inside a BFL (when it first drops below 832MH/s), I should see (ZLX) close to that "throttling temperature" just before it decides to throttle?

This is true. Should your unit for instance throttle at 67C, then that is usually the throttle threshold of your unit. Of course, the unit must be
in the same condition as it was the first time (enclosure closed/open, number of fans active, etc). Should one factor change, the throttle
temperature will change with it.


Good Luck,
BF Labs Inc.

[zefir]

Solved!

Tl;dr: dried-up thermal grease was causing thermal resistance between heat-pipe and FPGAs.

First off, thanks to all for your hints and suggestions. For me they didn't work, but they might be helpful for others with related problems.

Then, I need to apologize for calling BFL customer support crap. It is true that none of my emails I sent after ordering my Singles wasn't answered, but that were the times when probably every second miner overrun them with orders or questions. In contrast to that, my request for assistance in this case I sent yesterday got responded within hours with very helpful instructions. Sorry again.

Back to the problem. After none of the proposed approaches to improve cooling worked, I made sure that it is not an ambient temperature issue by running the device in a temperature chamber at 0°C. Same effect with throttling every several minutes and a total hashrate of less than 700MH/s - a strong indication that there was a problem with thermal conductivity between heat-pipe and FPGAs. Assumption turned out right as soon as I removed the heat-pipe: it was evident that the surfaces had only partial contact, since at one FPGA there was a larger blob of dried-up thermal grease that was holding the heat-pipe back from settling down. As a result, one FPGA had almost no contact to the heat-pipe, the other only partially.

I speculate that the heat-pipe was initially placed with one push-pin not fully locked and the grease started to dry-up at the loose side. Later during QA the push-pin was fixed, but the grease was already too viscose to be squeezed out evenly. Or something completely different...

I squeezed the blob manually and distributed it all over the FPGA with my finger to build a thin film, attached the heat-pipe back - et voilá, device is working at full speed with 815MH/s

Was too busy and didn't take any pictures, but it is quite obvious when you remove the heat-pipe.

[bitcoindaddy]

Solved! ....
I squeezed the blob manually and distributed it all over the FPGA with my finger to build a thin film, attached the heat-pipe back - et voilá, device is working at full speed with 815MH/s

BFL, does this void our warranty when we have to do such repairs? Are customers authorized to open the device in cases like this?

[tarrant_01]

When I mentioned replacing the thermal grease on my single that was throttling, they said I could try that and didn't mention the warranty at all.  There are no stickers in place that seal the enclosure. It's a good thing too for obvious reasons.  Quite a few of the singles have throttling issues it seems that require small repairs like the ones mentioned above.  Probably would be a good sticky for hardware or troubleshooting.  A guide on what to do with a throttling single.