RM750 whine at idle

[MagmaRules]

Hi guys,

 

So I decided to upgrade my old CX500M to a new RM750. Couldn't find a RM750x in stores.

After I switched the PSU I noticed an acute whine coming from the PSU. Seemed like it only happened while I was not actively using the PC like reading an article. I went to the store and they gladly replaced it for another RM750 saying it was coil whine.

Now I have the same noise with the new unit but I found out it stops after it "warms up". So if I play a game for 15mins for example it will then no longer have the noise at idle for a while. Eventually it comes back from time to time at idle after it "cools down".

I tried with the PSU fan facing down and facing up. Also tried connecting it to a different plug. It always has the noise.

Also no noise under load.

 

Considering my current build consists of a Ryzen 3700x and my old GTX 1080 its not really pushing the PSU so I imagine its pulling really low power at idle.

 

Considering both PSUs had the same noise at idle I'm assuming that this is the normal behaviour and other people don't hear the noise? I would expect not to have to use workarounds to get a normal usage out of my PSU. Never had any of these issues with my old PSU for 5 years.

 

Anyone else noticed this noise at idle?

[jonnyguru]

I went to the store and they gladly replaced it for another RM750 saying it was coil whine.

 

Weird. If they knew it was coil whine, I wonder why they replaced it anyway. Good service on them, I guess.

 

On the RM, it's normal. Below 10% load, the switching changes from LLC to burst mode in order to improve low load efficiency. Problem with burst mode is audible noise.

[MagmaRules]

Weird. If they knew it was coil whine, I wonder why they replaced it anyway. Good service on them, I guess.

 

On the RM, it's normal. Below 10% load, the switching changes from LLC to burst mode in order to improve low load efficiency. Problem with burst mode is audible noise.

 

That is unfortunate. Do you know if Corsair has another PSU that doesn't have this behaviour? As an alternative I would need to change to another brand like the Seasonic GX

[jonnyguru]

Is it really that loud? Should only be noticeable if your ear is right up against the PC.

 

You're going to find most PSUs after the end of this year will have the same "issue". It's necessary to meet the newest efficiency requirements which require 70%+ efficiency at loads as low as 2%.

 

The current RMx, RMi, HX and HXi do not have this feature as they have been on the market since before the efficiency requirement.

 

You could also try a lower wattage PSU. As you don't need anywhere near 750W, you're going to be in the < 10% range more often.

 

I suggest maybe an RM650x.

[MagmaRules]

Is it really that loud? Should only be noticeable if your ear is right up against the PC.

 

You're going to find most PSUs after the end of this year will have the same "issue". It's necessary to meet the newest efficiency requirements which require 70%+ efficiency at loads as low as 2%.

 

The current RMx, RMi, HX and HXi do not have this feature as they have been on the market since before the efficiency requirement.

 

You could also try a lower wattage PSU. As you don't need anywhere near 750W, you're going to be in the < 10% range more often.

 

I suggest maybe an RM650x.

 

I have fractal define 7 compact tower in my desk next to me. When at idle its dead silent. I also tend to be sensitive to this type of sounds :sigh!:.

 

I bought a PSU with 750W due to the new NVIDIA graphics requiring quite a bit more power and recommending 750W. But given the rest of my setup I would probably survive with 650W I guess.

[Kallex]

I have fractal define 7 compact tower in my desk next to me. When at idle its dead silent. I also tend to be sensitive to this type of sounds :sigh!:.

 

I bought a PSU with 750W due to the new NVIDIA graphics requiring quite a bit more power and recommending 750W. But given the rest of my setup I would probably survive with 650W I guess.

 

Just a word of warning, be cautious of underestimating the PSU requirement of new RTX 30x0 (I think that's what you're referring to). It's not the continous load only that needs to be enough, but also the short term voltage spikes that trip the PSUs.

 

If you Google around the topic, you'll see. It's not black magic, but its part of reason why the PSU requirement was that high. They always tend to overstate the requirements, but this time there is point to be made.

 

Given also the issues with RTX 30x0 its easier to RMA your card, if you can say that you meet the PSU requirement and its not the reason for instability or whatnot.

 

EDIT: I'm not saying 650W wouldn't do it, but if you can find out whether it has the characteristics (to tolerate the spikes) to match the RTX 30x0 requirements you're planning to meet.

Edited September 28, 2020 by Kallex

[MagmaRules]

Just a word of warning, be cautious of underestimating the PSU requirement of new RTX 30x0 (I think that's what you're referring to). It's not the continous load only that needs to be enough, but also the short term voltage spikes that trip the PSUs.

 

If you Google around the topic, you'll see. It's not black magic, but its part of reason why the PSU requirement was that high. They always tend to overstate the requirements, but this time there is point to be made.

 

Given also the issues with RTX 30x0 its easier to RMA your card, if you can say that you meet the PSU requirement and its not the reason for instability or whatnot.

 

EDIT: I'm not saying 650W wouldn't do it, but if you can find out whether it has the characteristics (to tolerate the spikes) to match the RTX 30x0 requirements you're planning to meet.

 

Thank you for the feedback. I guess the 3080 idle consumption would probably also "fix" my issue :D:

[Vegan]

Is it really that loud? Should only be noticeable if your ear is right up against the PC.

 

You're going to find most PSUs after the end of this year will have the same "issue". It's necessary to meet the newest efficiency requirements which require 70%+ efficiency at loads as low as 2%.

 

The current RMx, RMi, HX and HXi do not have this feature as they have been on the market since before the efficiency requirement.

 

You could also try a lower wattage PSU. As you don't need anywhere near 750W, you're going to be in the < 10% range more often.

 

I suggest maybe an RM650x.

 

I wonder of Corsair will introduce a new line of efficient PSUs for gaming

[Kallex]

Thank you for the feedback. I guess the 3080 idle consumption would probably also "fix" my issue :D:

 

Those cards can still be very efficient while idle ;-). But - speaking of the current state of the world... you *could* run something like BOINC or other generic scientific grid-computer with just 10-20% of your CPU, enough to keep it "off idle".

 

BOINC has enough options to keep it off when comp is not idle etc, limiting the CPU usage enough; possibly allow it to keep you off-idle, but not in too powerhungry mode (to introduce other unpleasanties).

 

While it would boost your electric bill also a bit, it would benefit for greater good. My (personal) company made a commitment to run those things overnight, which adds definite electricity costs, but puts our hardware for good use.

[MagmaRules]

So late last night I kept researching and found some threads about C-States.

I went into the BIOS and disabled them. The PSU has now stopped producing the noise.

 

Only time I hear it now is during the boot and 30sec-1min after the boot if I leave it idle.

 

Right now doing an experiment just leaving the computer at idle while I work on another machine to test the long term results.

 

The irony of having an efficient PSU but having to disable power saving features to avoid noise from the PSU :roll:

[jonnyguru]

The irony of having an efficient PSU but having to disable power saving features to avoid noise from the PSU :roll:

 

It's not ironic, really.

 

If the PSU wasn't so efficient at low loads, it wouldn't make the noise in the first place.

 

You want efficient, there's noise.

 

You don't want efficient, there's no noise.

[Pocah]

Unfortunately, the 3080 series have low power consumption when they are idle, so this is likely to be a common problem ~ people buying bigger PSU's but not using them at idle.

[Vegan]

There is a push to redesign power supplies to be > 70% at very lower power levels.

 

Not many models do that yet.