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Corsair Commander Pro: using 3-pin (voltage controlled) fans will fry the unit

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I've bought a Commander Pro this spring, to help make sensible fan speed control. MB headers are often limited in number, and placed inconveniently. I also believed this is a premium product and robust, and still believe that something quite critical such as a fan controller should be robust and should not fail. I mean, the device is not that expensive, but not cheap either and my cooling solution should be covered.

However, I'm really disappointed on the device. First, one of the ports stopped working. I changed the port - and though, well I need to bring this thing back to the store to get changed for a working one. Before I had time to do this (within a week) another fan port (the one I changed to) stopped working. And by stopped working in this case means, the fans stop and report (now correctly) 0 RPM.

At this point I should probably mention I'm driving 3-pin fans (with a splitter), well under the 1A limit (0.32A) of the per header limit. The device has <1A of fans connected to it in total (8 fans).

I was really quite disappointed finding from this three years old thread that this is, actually, a design fault, and also the fact there is no Corsair input on this issue in that thread or elsewhere.

Now, the obvious and only workaround is to not use 3-pin fans at all on the device, but use only PWM ones (save for changing the SMD transistors and adding some kind of cooling themselves). However, I really feel this limitation and design fault should be in the device description. A failing fan can cause hardware damage ranging from hundreds to a few thousands of dollars/euros/equivalent to the user. Luckily, in my case the 3-pin fans were not the only fans cooling the system radiators.

Now, I would like to hear Corsairs input on this: what do you think on this issue? Is there going to be a revised device (which sufficient cooling to the transistors in case 3-pin voltage adjusted fans are in use), and/or a documentation and firmware upgrade, which prevents the fans from being controlled in the first place on this clearly faulty by design device????

Also, I would like to hear from other users any recommendations for other, similar and reliable devices.

Any other thoughts on the issue are welcome, too. Am I being too rough on Corsair? I didn't get any damage on my devices, but this certainly does eat into trust on the company and their devices.

TL;DR: 3-pin (voltage controlled) fans can fry a transistor on the Corsair Commander Pro. This seems to be a design fault in the unit (see this link), and in my opinion that is not OK.

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First : did you set the fans manually to 3-pin or did you leave them on AutoDetect?

Second : Three fans on a single splitter doesn't work well (as you've discovered). This is pretty well known and well discussed on that thread (though you seem to conveniently ignore that). Also of note is that splitters are not officially supported on the Commander Pro - at all. So - your argument that this is "normal use" isn't quite accurate (normal use is no splitters). Also, going by the current rating on the fans themselves isn't always a good idea - the accuracy of those ratings varies pretty widely. I've measured fans using up to 50% more than the sticker claimed.

That said, it is an issue. It's particularly an issue with DC controlled fans. Once upon a time, these were the top tier fans and PWM was rare. That's not the case any longer - top tier fans these days are all PWM - which don't seem to have this issue. It seems to be DC fans (primarily) and related to the auto-detect functionality where the CoPro tries to detect if you have 3-pin DC fans or 4-pin PWM fans - hence, the question about setting them manually.

Your best resolution - without changing fans - is twofold. One, set the fans manually to 3-pin. Two - don't use more than 2 fans on a splitter.

As far as reliable ... I'm running 4 CoPros in various systems and have been for years. I've never had one fail. Ever ... and one of them is (currently) running 10 fans (a mix of QL and ML) + a XD5 pump. But ... nothing more than 2x splitters.

Finally ... on to resolving the problem with future products. It would seem that Corsair has - we've not heard much, if any, issues with the Commander Core having this problem. But then - the Commander Cores (both of them, the one with the Capellix cooler and the XT with the 7000X case) simply dropped support for DC fans and will work with PWM only.

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Hi DevBiker,

Thanks for your input.

I have to point out here, that I never found out that thread before my unit got broken. I wouldn't even found this forum if I wasn't troubleshooting an issue!

There is no facts in that thread I could be ignoring (conveniently or otherwise) - it is irrelevant to determine if there is an issue or not (it is useful for analyzing possible causes and helping users find solutions only). Users are (of course!) using their devices just by the documentation they get when they by the unit, they can not be expected to go searching on forums for additional information before using their devices! Especially on something which goes against common sense:

Common sense would suggest, one can use several fans from a one header. This is what users have been doing for decades with fan headers (up to a 0.5 or 1A limit depending on devices documentation). There is nothing pointing otherwise in the documentation(*) - it let's users understand these are regular fan headers, just as the ones we are accustomed to having in motherboards (this is, honestly, the assumption I've been also working under). Also, the maximum rating they are giving per header does not make any sense if one is not supposed to run more than one fan: I mean, are 1A(+) fans really that common?!??

I agree the amperage marking in a fan can not be relied on too much - however here we are talking about one third of the maximum rating. Also, some users have broken their units just by using one single fan.

Reading that thread, I wouldn't trust the unit even for running two or even a single 3-pin fan. What I'm going to do, I will be replacing the unit under warranty, replace the voltage-controlled fans I have currently, and use it only for PWM fans from now on (despite this flaw, this seems to really be only controller which can be programmed via USB). As far as I understand, there is no issues with PWM controlled fans; problems arise when a transistor tries to drop the voltage, but needs to dissipate I*(12V-V_goal) amount of power as heat, and this has not been taken into account when designing the device.

The real issue here (from users point of view) is unexpected breakage, and lack of reaction from Corsair.

But thanks for your suggestions, I will take them under consideration!

*) There is one persons opinion in the thread I've linked who seems to think the documentation suggest one is not supposed to use splitters; I must admit I find that interpretation quite weird and far-fetched, though in principle, it is a grammatically correct interpretation.

Edited by Wild Penguin
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that transistor was clearly underspec'ed and can pop easily when using splitters. The main trouble with corsair, again, is the lack of proper documentation. I wouldn't consider the forum as a replacement for documentation.

But i guess advertising in the box that the CoPro can't use splitters because it may fry the unit isn't good for sales.


That said, it's an old design. 3 pin fans are the exception now, and using PWM only solves the issue completely since there's no need to drop voltage at all (no heat, not popping drivers). If they ever update the Commander pro, i'd be surprised if they still supported DC controlled fans.

I actually used a Copro for more than a year with 3 fans per header, in PWM, without issues. if they were 3 pin, it would probably have popped fairly quickly

The best fan controllers i know only support 3 pin fans through plug-in modules with beefy transistors and heatsinks, and they are not cheap.

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1 hour ago, LeDoyen said:

that transistor was clearly underspec'ed and can pop easily when using splitters. The main trouble with corsair, again, is the lack of proper documentation. I wouldn't consider the forum as a replacement for documentation.

Can't argue with that. The most egregious example was the V2 series coolers that were powered from the fan header. Nowhere in the documentation did it mention to put the header on 100%.

1 hour ago, LeDoyen said:

But i guess advertising in the box that the CoPro can't use splitters because it may fry the unit isn't good for sales.

I really doubt that was the reason for it. The documentation provided is the minimum required and leaves a lot out. And technical folks usually aren't the best at documentation either. More recent items are better but that's not a very high bar. That said, it's pretty much the same way across the industry - it's extremely rare to get documentation with a hardware device that deserves the title "documentation".

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