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 Post subject: Server motherboard fan control
PostPosted: Mon May 27, 2013 8:40 pm 
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Joined: Mon May 27, 2013 8:13 pm
Posts: 3
Hello,

I've been doing some research on how to go about replacing or outright removing fans in servers. I'm not entirely sure of my limitations on how much I can get away with from a programming standpoint.

Almost all servers freak out if no fans are attached (like if I did water cooling for example) or they require a minimum RPM that tends to be higher than one would want for "quiet" cooling.

Obviously servers are designed for the cooling solutions they have so you generally don't want to be tampering with it, due to the environment the servers would be in however I can get away with it.

What are my options? Is there a way I can go about programming the BCM to lower RPM thresholds or outright remove the requirement? Is the BCM even the correct thing to reprogram to do this? Would it need to be done BIOS level? I've seen mention of IPMI but that looks like it simply reads back data, I don't think you can directly control fan thresholds with it.

Would a hardware mod be possible? A pigtail perhaps that fakes out the sense line?


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 Post subject: Re: Server motherboard fan control
PostPosted: Tue May 28, 2013 8:45 am 
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Joined: Mon May 16, 2011 11:23 am
Posts: 623
Location: Germany
You will void any warranty whatsoever by tinkering with any hardware/software. If you use those servers to earn money, having no warranty could ruin your business within a few days.

If you do not make money with those servers, then i'll highly doubt you will be able to silence them without risking severe damage if the servers are taxed (think of a single process going beserk and creating 100% cpu workload). You could opt for a sound dampening enclosure/rack.

And finally, no, i haven't tried to silence any server hardware because we all know before that those will be loud and noisy, so we plan to store them in a separate room and do plan on using air-cons to keep ambient around 20-25°C.


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 Post subject: Re: Server motherboard fan control
PostPosted: Tue May 28, 2013 9:55 am 
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Joined: Tue Nov 02, 2004 12:22 pm
Posts: 1812
Location: Guatemala
I had a bad experience with SUPERMICRO MBD-X9SCM-F-O + Scythe Kama FLEX PWM 120 SA1225FDB12H-P 120mm PWM Fan, i used a Akasa Flexa FP5 PWM 5-Way Splitter - Smart Fan Cable (AK-CBFA03-45) to connect most of the fans. In theory all was good, but in practice was a nightmare, the bios sometimes see the fan as no rpm and bumps them to their max 1600rpm, to drop them down to 300rpm and again up.... so it becomes an endless cycle, the outcome is a breathing server.... really annoying, every 10sec goes to max speed and slowly down. I wrote to Supermicro to see if there was something i could do... or a bios revision, but i simple couldn't stand it, and just went with standard 3pin fans, low rpm and left it there. Since my experience there has been 2 new bios, specially one for ivy bridge support, not sure if they fixed my issues with Scythe fans, but it would ended up much quieter than what im running atm, at 300rpm was dead silent (aside from all the hdds), but i never tried other fans, but would have loved to use my scythe fans.

Btw if i loaded the cpu the breathing behavior would disapear, i did some prime95 to test some and the CPU was in fact being ramp up, very nicely if i might add, and the rpms stayed steady, was more when it was in idle and the mobo had the rpms to low where it freak out. If i could just put like a threshold so it didnt lower from that would been great, but didnt see anything like that on the bios. Personally i think if they fix this issue, it would be great to pair some Scythe Slipstream PWM fans with a supermicro mobo.

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 Post subject: Re: Server motherboard fan control
PostPosted: Tue May 28, 2013 11:39 am 
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Joined: Mon May 27, 2013 8:13 pm
Posts: 3
Pappnaas wrote:
You will void any warranty whatsoever by tinkering with any hardware/software. If you use those servers to earn money, having no warranty could ruin your business within a few days.

If you do not make money with those servers, then i'll highly doubt you will be able to silence them without risking severe damage if the servers are taxed (think of a single process going beserk and creating 100% cpu workload). You could opt for a sound dampening enclosure/rack.

And finally, no, i haven't tried to silence any server hardware because we all know before that those will be loud and noisy, so we plan to store them in a separate room and do plan on using air-cons to keep ambient around 20-25°C.

The servers don't have any warranty, they are ML350 G5's that I got for free as a client was upgrading.

As I said in my post, I can get away with mucking with the fans due to the environment the servers will be in.

I guess I should read up on how the fan RPM sensors work to see if there is a way to lie to it..


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 Post subject: Re: Server motherboard fan control
PostPosted: Tue May 28, 2013 7:38 pm 
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Joined: Sat May 11, 2013 8:33 am
Posts: 106
I've never heard of a warranty paying for down time or getting replacements delivered fast enough for any type of enterprise application.

On the software side I know many people who make their living futzing with software in enterprises applications they don't have warranties either.

What they do is run virtual machines that can migrate to different physical hardware in case of a fault and test new software in a virtualized environment before they roll out changes.


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 Post subject: Re: Server motherboard fan control
PostPosted: Wed May 29, 2013 3:11 am 
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Joined: Mon May 16, 2011 11:23 am
Posts: 623
Location: Germany
Some companies i did work for had their servers covered by 24/7 4h on site support/warranty. And in a few cases they were forced to use this support service - and in general the supporters didn't screw up and delivered a solution to keep downtimes as small as possible.

Back in the days Compaq flew in (from Taiwan to Frankfurt, as the supporter claimed) a 80 GB SCSI-HDD for our NT4 PDC (that really was a IBM 160 GB drive with a special compaq firmware) because none was available in european compaq warehouses.


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 Post subject: Re: Server motherboard fan control
PostPosted: Wed May 29, 2013 7:53 pm 
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Joined: Mon May 27, 2013 8:13 pm
Posts: 3
I have no doubt that if these were under warranty that HP would void it if they knew what I had in mind. In a production environment I would never think to mess with them. G5's are actually extremely quiet for a server anyways, they were the quietest thing in the clients rack by far.

But none of that is really the point of my post. I have them now and I want to tinker.

So far I've found out the ML350 G5 requires fans of adequate speed be plugged in to fan headers 1 and 3, it doesn't care about anything else. I also determined the pin out for the stock fans:

Code:
|____________________________|
|_____|_____|_____|_____|____ |
  PWM  Sense   12V    GND    GND


So it's actually a reversed standard 4pin fan connector with the ground line being split for the 5th pin. They actually split the single ground line to two right before it goes in to the connector.

Crimp part number: 08-50-0114
Housing part number: 22-01-3057 (you can get both of these at mouser or newark for example).

There are no settings at all in the BIOS to control the fans. The server will boot up and get past the initial BIOS splash screen and then complain about the fans and then it reboots.

I read that the BCM/SDR/IPMI are all under the ILO controller so I'm looking in to ways to get my fingers into ILO at a low level. It concerns me that during the BIOS post it complains about the fans though, this might ultimietly be controlled by the BIOS and not ILO. This might be a good thing though, it seems like there is a bit more info out there on BIOS hacking.


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