CRS354-48G-4S+2Q+ (Heat issue?)

Sharaf · March 30, 2020, 12:56pm

Hi,
I recently bought CRS354-48G-4S+2Q+

After un-boxing and powering it up, I noticed fan speed is ramping up loudly. I logged into ( WinBox → System → Health ) to check Temps, I noticed that CPU temp is around 62 degree Celsius - IDLE (not connecting any ports hence no traffic or load). Is this normal? and If so, when should I worry regarding heating and temp issues?
Also, anyone had a successful chance reducing fan noise (maybe Noctua fan replacement? - I know that would decrease static air pressure but maybe temps would be manageable?)

Thanks in advice, and info would be appreciated.

Regards,

planetcoop · March 30, 2020, 2:04pm

I have also experienced the high temps. When i add traffic, the CPU reaches 72C. I have removed the lid and added a 4th fan, a noctua 40mm blowing at an angle on the cpu. This keeps the temp in the high 40s or low 50s with traffic. I was able to use the rubber mounting with the fan kit to hold and wedge it near the CPU.

Hope that helps.

https://www.amazon.com/Noctua-Cooling-Blades-Bearing-NF-A4x10/dp/B009NQLT0M/ref=sr_1_2?dchild=1&keywords=noctua+40mm&qid=1585577004&sr=8-2

Sharaf · March 31, 2020, 9:17am

Thank you for your input!

I wonder how you managed to attach the fan the way you described it?
What I currently planning is to fix a fan 40x40x10 mm behind SFP+ ports angled (somehow?), pushing air towards the CPU, and replace all the fans with Noctua 40x40x20 mm in order to reduce noise levels, and this way perhaps the fans would be continuously running with less noise since temps will rise (due to less static air pressure resaltant from replacing the fans) and fan controller will kick in to cool the device 24/7 or based on Temps.

All this idea is still theoretical, and need tobe tested first. I will try to get the fans and figure out a way to implement it.

And if there are any other ideas and thoughts, I appretiate it.

planetcoop · April 1, 2020, 3:15am

In the noctua fan kit it has the rubber pull grommets. I pulled them into a loop and it sits between the ports and the cpu heat sink at a near 45 angle. I will have to take it apart to get a pic, but that is the right idea.

Here is a pic of the stats in the mean time.

Sharaf · April 1, 2020, 9:02am

Thank you for your reply.
I think I will install a fan 45 degree on CPU and fix it firmly with a bracket to the device case (I will insulat it electrically just in case or maybe I will find non-conductive bracket) as shown in the pic below:

planetcoop · April 1, 2020, 6:41pm

Nice work, i will have to keep an eye out for a good bracket.

Sharaf · April 2, 2020, 5:10pm

Nice workaround, and now I understood how you used the rubber to sit the fan

Also, for anyone wants replacing “all stock fans” with Noctua 12v fans, the fan won’t start until it receives proper voltage from the header (in which header provides when temp reaches 66C+) , unlike the stock fans which will ramp up gradually and benefiting from increasing voltage provided by the header and fan controller.

As I’m planning to replace all the stock fan with Noctua’s fans, since I can’t control the stock fan RPM to control the noise through software, and at the same time I don’t want to worry reaching high temps each time to provide proper 12v threshold for Noctua fans, I will do the following steps:

I will install a fan pushing air towards CPU as show above.
I will replace all the fans and connect the wires of the fan header (Black and Red wire only) to PSU J1 OR J2 header, so I will run 24/7 (Quietly)
Yellow wire will be connected to fan header corresponding to its original location on the board, that will enable me get readings of the fans RPM through Winbox

Am I missing anything with this idea before implementing it?

expert · April 4, 2020, 8:55pm

I did similar mod of my new CRS354-48P-4S+2Q+ with 4x Noctua NF-A4x20 FLX and one tiny fan for CPU, connected via Y-adaptor to fan1 header. So far, all good.

Sharaf · April 5, 2020, 2:10pm

Thank you very much for sharing this!
If I may ask, can you share your temp and RPM result under a reasonable load with your mod?

Regards,

expert · April 5, 2020, 6:37pm

The following metrics were captured when the device is idle (no traffic, no attached devices):

     cpu-temperature: 56C
  board-temperature1: 36C
        psu1-voltage: 27.1V
        psu2-voltage: 53.7V
        psu1-current: 0A
        psu2-current: 0A
          psu1-state: ok
          fan1-speed: 4215RPM
          fan2-speed: 4230RPM
          fan3-speed: 4440RPM
          fan4-speed: 4455RPM

Once I have metrics under load, I will post them here.
I’m also thinking about adding 2 more Noctua fans to the back side of the device (to be connected using Y adaptors which are included)

Sharaf · April 12, 2020, 7:00pm

Just an update, I installed 4 x noctua fans as the following steps above, connected ti directly to J1 PSU cable to power them up 24/7 and connected the PWN signal reading to third pin. So far so good!! Temps around 52-53c (idle) and nosie is significantly reduced.

One concern is that if the PSU which the fans are connected to now fails, the fans will stop. I will try to fiugre something out in this case. Seems I will only connect power to PSU with fans and leave the other one as spare. If the PSU fails, the switch will turn off.

Sharaf · April 13, 2020, 8:22am

Here is picture of my final installation:

Hope someone will find this useful. Many thanks for the help!

billybreakfast · August 4, 2021, 3:47pm

Nice workarounds guys ! Stock fans are really unbearable. Ive just replaced them with 3 noctua a4x20 flx and closed the lid. It’s better than stocks ones but still noisy…

I need to go further and your tips are great help.

One question thought: as someone closed the lid after fans replacement with great result (silent under load) or you all decided to keep the lid removed ?