AX1600i Fan Running Continuously

[jwoolen]

I’m experiencing a strange issue with some TRX40 motherboards with a Corsair AX1600i power supply when I increase the memory frequency. If I use a motherboard with the XDPE132G5C controller and 16 phase power delivery (I’ve tried an Aorus TRX40 Xtreme and an MSI Creator TRX40) and increase the memory speed from 2133, it causes the PSU fan to run. The AX1600i is a monster, capable of running fanless up to 800W. I also have a Zenith II Extreme Alpha. With the Asus board, the 0 RPM mode of the AX1600i functions properly when running the memory at XMP (3600MHz 16-19-19-39, 1.35V). I was able to apply 600W of load to the power supply and the fan never came on, with the PSU temperature topping out at about 39 degC. With the Aorus TRX40 Xtreme, as soon as the XMP settings are applied, the fan comes on and runs at around 460 RPM. If I apply the same 600W load using the Aorus board, the fan ramps up to around 800 RPM. As long as I run the memory at 2133MHz, the fan behaves normally. I’ve played around with other settings in the BIOS and it seems to be the memory frequency specifically that makes the fan spin up. Increasing the memory voltage doesn’t make the fan spin up.

 

I really like the lane allocation of the TRX40 Xtreme vs. the Asus Alpha, since it doesn’t disable this if you use that like Asus board does, but the first priority of my build is for it to be as quiet as possible. There’s really no reason for the fan to be running on the AX1600i with the Aorus board. I’m thinking there has to be something I can change in the BIOS to keep the fan from running, but I can’t think of anything. Could it be the difference in power delivery design that is causing this? The Aorus board actually draws a little less power than the Alpha, so I don’t understand why the fan is spinning up. Even during idle with the PSU temperature less than 30 degC and power draw less than 250W the fan is running. The temperatures and load values were taken from Corsair Link 4.

 

Any help with or explanation for this would be greatly appreciated.

[jonnyguru]

I'm guessing you're using the TRX40 because you have all 8 RAM slots populated?

 

The problem has to do with increased load on the +5V, which is what the RAM uses for power on that board.

 

The DC to DC for the +5V inside the PSU is not passively cooled (no heatsink), so when you get close to the +5V's capacity, the fan has to kick in to actively cool the MOSFETs.

 

You'll see that using a lot of RGB devices, which also uses the +5V, has the same effect on the fan controller: https://forum.corsair.com/forums/showthread.php?p=1046700 The conversation becomes relative to your situation starting at post # 6.

[jwoolen]

Thanks for that very informative response! I am indeed running 8 16GB sticks. I also have 8 SATA SSDs and a fan hub driving 6 fans connected to the PSU.

 

Your explanation and the information in the linked thread make a lot of sense, but I don't understand why it doesn't happen with the Asus board.

Edited November 12, 2020 by jwoolen
Typos

[jwoolen]

I took some screenshots in LINK with the Aorus board and the Asus board. The Aorus board is indeed using a lot more power on the 5V rail. I wonder if there is anything I can do in the BIOS to tame it.

 

Aorus TRX40 Xtreme

 

 

Asus Zenith II Extreme Alpha

 

Edited November 12, 2020 by jwoolen

[jonnyguru]

Thanks for that very informative response! I am indeed running 8 16GB sticks. I also have 8 SATA SSDs and a fan hub driving 6 fans connected to the PSU.

 

Your explanation and the information in the linked thread make a lot of sense, but I don't understand why it doesn't happen with the Asus board.

 

The Aurus board might be regulating the RAM from the +3.3V rail.

 

In standby, your RAM keeps it's memory profiles saved by using the +5VSB. So it may be easier to use the same regulator to regulate your RAM from the +5V instead of any other power rail. +3.3V is ideal because it's closer to your RAM's required voltage, but it's still an extra part on the board.

[Vegan]

DDR4 RAM is fed from the regulators power and it runs at 1.2-1.35V. Not much uses 3.3V anymore. 5V is used by the USB mostly for support BCC 1.2 charging power etc.

 

This is why board have 2 EPS12V cables so that it can have as much power as needed for slots which can use a fair bit.

 

8 sticks of RAM is < 8W of power

Edited November 15, 2020 by Vegan

[jwoolen]

Not sure if it could be a contributor, but I've tried two boards with the XDPE132G5C VRM controller (Aorus TRX40 Xtreme, MSI Creator TRX40) and they both cause the fan to behave the same way. I didn't monitor the amperage with the TRX 40 Creator.

 

It's definitely related to something that changes when the memory speed is adjusted. I reduced the memory speed to 3200 and the fan speed fell to about 360 RPM. With the memory speed set to 2133, I can get the 0 RPM mode to work, but it doesn't last as long as with the Asus board. I simply can't run my memory at that low of a speed to get the fan behavior I desire. I really want to use the Aorus board, but if the fan is running now with a 1660 Super, it's really going to run with an 3090 (assuming they'll ever available for purchase again). I want to keep my system's fan noise to a minimum. Nothing is quieter than 0 RPM. The Asus board gives me that. Unfortunately, the Aorus does not.

 

@jonnyguru

I really miss your power supply reviews. I leaned on your review heavily when I decided to get the AX1600i, and it has not disappointed. I really appreciate you taking time to respond to my post!

 

@Vegan

Thanks to you as well!

Edited November 15, 2020 by jwoolen

[jonnyguru]

DDR4 RAM is fed from the regulators power and it runs at 1.2-1.35V. Not much uses 3.3V anymore. 5V is used by the USB mostly for support BCC 1.2 charging power etc.

 

This is why board have 2 EPS12V cables so that it can have as much power as needed for slots which can use a fair bit.

 

Right. But there is no 1.2-1.35V output from the PSU.

 

And the EPS12V connectors are for CPU.

 

So, I'm not really sure what point you're trying to make.

 

RAM uses +5VSB when in standby. It uses either +3.3V or +5V to regulate down to < 1.35V when not in standby. Not sure why you're arguing that point.

[jonnyguru]

It's definitely related to something that changes when the memory speed is adjusted. I reduced the memory speed to 3200 and the fan speed fell to about 360 RPM. With the memory speed set to 2133, I can get the 0 RPM mode to work, but it doesn't last as long as with the Asus board. I simply can't run my memory at that low of a speed to get the fan behavior I desire. I really want to use the Aorus board, but if the fan is running now with a 1660 Super, it's really going to run with an 3090 (assuming they'll ever available for purchase again). I want to keep my system's fan noise to a minimum. Nothing is quieter than 0 RPM. The Asus board gives me that. Unfortunately, the Aorus does not.

 

If you can devise some sort of buck converter that takes power from the +12V of a Molex, for example, and replaces the +5V pins on the 24-pin, you could probably circumvent the load on the AX1600i's +5V buck converter, eliminating the need for the fan to kick in.

[Vegan]

Right. But there is no 1.2-1.35V output from the PSU.

 

And the EPS12V connectors are for CPU.

 

So, I'm not really sure what point you're trying to make.

 

RAM uses +5VSB when in standby. It uses either +3.3V or +5V to regulate down to < 1.35V when not in standby. Not sure why you're arguing that point.

 

Just trying to make clear that RAM power consumption is negligible vs other components

 

Anyway back to the problem with the PSU Fan

 

Zero fan is more temperature related than power related. So if the TRX40 box is running hot that might trigger the PSU fan.

 

Maybe the OP can post some photos

[jonnyguru]

Zero fan is more temperature related than power related.

 

No. It's not.

 

The fan controller MCU uses an algorithm that consists of temperature, +12V load, +3.3V load, +5V load. Each setting has it's own threshold. The PSU can be ice cold, but if the +5V load is high, this will still trigger the fan.

 

Not sure why you feel the need to constantly contradict me. It's only causing confusion for the end users.

[Technobeard]

Just to be clear, jonnyguru's a Corsair employee - listed here: https://forum.corsair.com/forums/showgroups.php

 

He'll be the best source of information on how our PSUs work.

[jwoolen]

Just to be clear, jonnyguru's a Corsair employee - listed here: https://forum.corsair.com/forums/showgroups.php

 

He'll be the best source of information on how our PSUs work.

 

He's also a PSU guru. I'm very grateful for his input. He helped me identify the reason for the fan running. I'm just going to stick with the Asus board since everything works like it's supposed to when I use it.

Edited November 16, 2020 by jwoolen

[jwoolen]

I had been having some issues with the Asus board so I ordered another Aorus TRX40 Xtreme. This time I received the 1.1 revision of the board. With the new Aorus board, the 0 RPM mode functions correctly and the power draw on the 5V rail is way down compared to the 1.0 revision. Not sure what's different, but I wanted to share this observation.