Quieter fans for a DCP2K4?

[Ryan Gallagher]

Has anyone ever done this mod or considered it? I expect they are just server chassis sized fans... but maybe it is actually the power supply fans that are to blame for the noise.

Our DCP2K4 is moving to cover the room left by the loss of cert on the prior GDC IMB. But this room does not have a sealed FOH/Projection booth area. The Christie has an enclosure to reduce noise, but the fans in the 2K4s are screamers... and the equipment nook to the left of the FOH operators area will likely be a new sound problem, or at least that is my premonition once we get it in there tomorrow. Adding a door to that area would not be easy, plus the heat build up would adversely impact the CP750 too.

[Marcel Birgelen]

Well, this is at your own risk obviously, but first make sure at what voltage the current PSU fans use and if they're PWM controlled or not. A good estimate of the airflow needed should also be done, in order to avoid your PSUs from overheating.

I've not replaced fans in a DCP2K4, but in switches and several big box machines. My go-to-alternative for silent fans is Noctua, don't know how available they are at your side of the pond.

[Marco Giustini]

Too many people (myself included) made the assumption that Noctua fans are "just better", replace a noisy PSU fan without thinking too much and only years later realise the selected Noctua fan had like 1/10th of the airflow (hence it's quiet!) and cooked the PSU to death! (fun fact, I fixed that PSU and then wired the same noctua fan directly to 12V as the original fan was being temperature-driven and kept at 1/2 of its rated voltage to keep it quiet).

That said, the DCP-2K4 is a noisy beast because of the PSUs mainly. Those tiny-high RPM fans run at silly speeds. And yes, if your room is temperature controlled, you probably don't need such airflow either. After all the 2K4 is a glorified PC.

To remove most of the noise I'd replace the stock PSU with a standard ATX PSU. Mind you, you'd be losing the redundancy though.
For those (60mm?) internal fans, you can find alternatives but make sure they have decent airflow. That said, I'd imagine neither the CPU nor the MB need a huge amount of cooling in a temperature-controlled room.

And since you're there, replace the thermal paste under the CPU cooler, I'm sure it's very much dry and useless by now.

[Marcel Birgelen]

Yeah, you need to check your airflow... Maybe, also start with one PSU first, see how it behaves. Don't throw away your old fans either...

Then again, even at comparable airflows, Noctua fans are more silent than your average cheap-o Chinese fan. They will never be completely silent though... There is no magic.

When we replaced our stack of aging Cisco routers and switches with a shiny new pair of Juniper switches in the booth of our screening room, the problem was that I could hear the high-pitched sound of those PSUs in the last row of the screening room, most likely leaking through the projection window. I replaced those with 24V Noctua fans with slightly lesser airflow, but since the booth is air-conditioned, that didn't turn out to be a problem. Those have been chugging along since the last 5 or so years...

[Marco Giustini]

Marcel, those fans are 30mm high-speed ones, they sound like jet engines. I believe they go up to 10k rpms. I don't think there is anything quieter to replace them with. The ones at the back of the server though can be replaced with something quieter - or maybe just slowed down: servers always expect the "worst case scenario" and I believe Doremi is using low power CPUs so maybe that amount of airflow is not required in a temperature-controller room.

[Marcel Birgelen]

Are they 30mm? if so, that would disqualify Noctua all together. The smallest ones Noctua makes are 40mm. And yes, those small, high-speed fans sound like jet-engines. If you have a modern 1U machine or switch, it's loaded with those and it sounds like 100 drones taking off.

The fans I replaced on the Juniper switches' PSU were 40mm and it does make a whole lot of difference. While they're not silent, they're sufficiently more silent so they're no longer audible inside the screening room, which is what I wanted to achieve. The airflow is about 15% reduced, compared to the original ones, but even when running at full-speed during boot, they're way more "silent" than the original ones.

[Marco Giustini]

Maybe there is a dual-PSU enclosure that can fit in the Doremi space which is a bit quieter. The fastest solution would be a (good quality) PC power supply. The OS might complain about it though, those PSUs often have a communication line with the MB to pass their status.

[Marcel Birgelen]

There are hacks where people run those machines on standard ATX PSUs, but I would not want to propose such a hack. In this case, it doesn't seem that the OS complains, it's not a tightly integrated system like a more modern Supermicro, Dell or HP server.

[Marco Giustini]

I've never paid attention to how the PSU is wired in - but Doremi still use server boards, right? Is it not wired to the PSU status bit, whether it's I2C or a simpler High = good Low = bad?

[Dave Macaulay]

Realistically the chassis is overcooled. With a dead CPU fan they run fine for an extended period staying cool enough from the windstorm in there. But as has been said, it's the PSU fans that make the most noise. On boot the chassis fans run at top speed for a while then they slow way down as the system loads and the speed control sees a low temperature. It's really loud for a few seconds.
The PSU fans are small, high rpm, and I think two are stacked (not sure about the 4U ones) loud and not really serviceable. I have swapped a fan from a blown one with one that just has a squealing fan but it wasn't super easy.
Yes you could put a single ATX supply in, replacing the dual unit. You lose the redundancy of course. The beeper alarm is part of the dual chassis. The board won't know it was swapped.
I don't recommend that but it should work fine. I have not tried it but have tested bare boards With a standard ATX power supply - we got the same motherboards on eBay and had to test them with the CPU Doremi uses, revise the BIOS settings, etc.

[John Thomas]

We have one ShowVault (same chassis as 2K4) where we did exactly this experiment -- replaced all chassis fans with Noctua. It is quieter, but the majority of the whine that you're trying to get rid of is in the power supply fans. As others have said, if you want a truly quiet SV or 2K4 you'll want to replace the entire dual power supply situation with a quieter, equal- or higher-wattage single power supply. Should be a piece of cake with the right adapters to make a newer-style supply plug into the older mobo and raid backplane. Hardest part would be fitting the replacement supply into the chassis nicely.

[Marcel Birgelen]

I've never paid attention to how the PSU is wired in - but Doremi still use server boards, right? Is it not wired to the PSU status bit, whether it's I2C or a simpler High = good Low = bad?

There is no I2C, just a small PCB without any real breakout to the rest of the system that handles the dual PSU situation. I doubt it communicates with anything on the mainboard, other than standard ATX signaling (raise POWER OK to 5V+). In the end it outputs classic ATX power to the mainboard and standard molex power to the RAID backplane. Like Thomas indicated, using an ATX PSU to power the thing IS pretty easy, still this isn't going to be just a simple fan-replace hack anymore.

[Ryan Gallagher]

Thanks all. This is not the type of experiment my management would go for unless we get complaints. But I'll suggest the ATX supply possibility if and when we come to that head. The chassis fan is easy, but as you said, unlikely to be the source of the higher pitch noise.

They may opt for some sound deadening curtains to hang on the entryway of that little closet, but there is not direct AC in that space, just gets what flows in there through the entryway.

It was noticeably louder to the small house (especially at the back), so i'm expecting something may have to happen.

[Marco Giustini]

I was mistaken BTW, those jet engine fans are 40mm, not 30. But at 5CFM I wouldn't consider them ?

[Marcel Birgelen]

I was mistaken BTW, those jet engine fans are 40mm, not 30. But at 5CFM I wouldn't consider them ?

According to Noctua, their 40mm fans have an airflow of 8,9 to 9,4 m3/h, which is pretty close to 5 CFM, which is about 8,5 m3/h. So, on those specs alone it seems entirely doable.