RM750 (2019) : a few questions about burst mode

[Cifer]

Hi,

For a future high-end build (nvidia 4000 GPU in mind, no mining), I am considering the dual-PSU option for maximum silence (2x 2019 RM750).
I am already shopping for the PSUs because I am very sensitive to electrical noises (coil whine and such), and want to take actions before I find myself shopping in a market where all PSUs come with burst mode.

I understand that this is something PSU manufacturers are forced to do in order to follow new efficiency requirements. I am not blaming them.
It's just that I've heard horror stories caused by said burst mode, and wish to know if I should just pay a little extra in order to get a dead silent PSU at low loads (2018 RM750x to be precise).

I have read the review of the non-x RM750 Aris has published, but couldn't find any info about exactly when the PSU leaves burst mode.

Therefore, my questions are the following :

1/ Do we know how many watts one needs to draw from a 2019 RM750 non-x for it to leave burst mode?

2/ Are there any tricks available to force non-burst mode? (would an increased load on the minor rails help in any way?)

3/ Would a high end AMD CPU (5950x) draw enough power on idle to make an RM750 leave burst mode if coupled with a high power-draw GPU?
Would an overclock on the CPU help, even at idle?
(The plan is to put all of the CPU load + 24pin load + 1 VGA cable on the first RM750, while the other RM750 will be providing power to the GPU only via 2 other VGA cables)

4/ When the PC is turned off, it still draws power, which will probably force burst mode. Does enabling ErP prevent burst mode from occurring?

5/ Based on the answers to the questions above, should I just bite the bullet and buy 2x 2018 RM750x now that they are still available and call it a day?
(Where I live, RM750 costs around 180 USDs, while the 2018 RM750x costs 215 USDs).

[Guest]

The burst mode on the RMx doesn't make noise.

 

[Cifer]

13 hours ago, jonnyGURU said:

The burst mode on the RMx doesn't make noise.

 

Thanks for the info !
I therefore deduce that the burst mode on the non-x does make noise... which means I dodged a mighty bullet right there...

Since I'm going with a dual-PSU setup, I've been trying to gather info on how to make the whole thing work, which inevitably brought me to this article of yours :
http://www.jongerow.com/PSU_relay/index.html

You could have done what miners do, but instead you went out of your way to include relays.
Could you please explain why?

[Guest]

9 hours ago, Cifer said:

Thanks for the info !
I therefore deduce that the burst mode on the non-x does make noise... which means I dodged a mighty bullet right there...

No.  The RM doesn't make noise either.   It's literally the same platform.  I just missed where you asked about both.

 

You run into noise with burst mode when you literally drop an IC that supports it in place of another IC that doesn't without changing anything else.  A lot of PSUs have done this and these are the ones that make the noise.

 

9 hours ago, Cifer said:

You could have done what miners do, but instead you went out of your way to include relays.
Could you please explain why?

Don't remember.  That thing was written 15 years ago.

 

I think the signal was too weak to trigger the second PSUs.  But I've also just split the power good across two PSUs and have had that work too.

[Cifer]

13 hours ago, jonnyGURU said:

No.  The RM doesn't make noise either.   It's literally the same platform.  I just missed where you asked about both.

 

You run into noise with burst mode when you literally drop an IC that supports it in place of another IC that doesn't without changing anything else.  A lot of PSUs have done this and these are the ones that make the noise.

 

Don't remember.  That thing was written 15 years ago.

 

I think the signal was too weak to trigger the second PSUs.  But I've also just split the power good across two PSUs and have had that work too.

Thanks a lot for all the help !

[Cifer]

Hi,

I'm back with more questions pertaining to this setup...

Since I didn't need to buy the PSUs right away, I chose to wait until I first get my hands on the GPU.
But there has been some change to the market that might drive me to buy right now.

One of the most popular PC shops in my country (Morocco) has been doing something quite unusual for the past few days : they have restocked the 2018 RM750x , and they're selling it at a really decent price (when compared to the rest of the moroccan market) : $157 instead of the usual $210.

https://www.ultrapc.ma/43-alimentations-pc

@jonnyGURU : Has Corsair been heavily discounting these EOL units to get rid of whatever was left in stock ?
If not, should I just see this pricing as a red flag? Could it be that they are reselling refurbished units as brand new?

[Guest]

1 hour ago, Cifer said:

Has Corsair been heavily discounting these EOL units to get rid of whatever was left in stock ?
If not, should I just see this pricing as a red flag? Could it be that they are reselling refurbished units as brand new?

I know that some of the older, lower wattage (650W and 750W) have been discounted.

 

But whether or not they're selling refurb as new:  The part number on the PSU's box would have an "/RF" in it if it were a refurb.  Example:  CP-9020179-NA/RF

[Cifer]

On 4/1/2022 at 5:43 PM, jonnyGURU said:

I know that some of the older, lower wattage (650W and 750W) have been discounted.

 

But whether or not they're selling refurb as new:  The part number on the PSU's box would have an "/RF" in it if it were a refurb.  Example:  CP-9020179-NA/RF

I have asked them to send me a picture of the PSU, the part number doesn't have the /RF :



Thanks again for your precious help !