@Martin1958 I stumbled across the Seasonic Focus Platinum range some time ago and was attracted by the suggestion that it was a 90% unit when supplying a low output, which suited me because my machine stays on all day so the less power it takes when left unattended the better.
Sadly Seasonic have moved on from that range but some units come up from time to time used on Ebay and both my second 550W unit and the 650W unit were “open box” units with all the connectors etc. intact and have been running just fine since.
You are right that each recommendation is going to add a safety margin and DxO are bound to do that when your 500W unit appeared to be failing under the load of a DxO export!
I am concerned about the labelling of the document you pointed to
@Prem I never worked in the electronics industry but have dabbled in electronics for many years, although I never owned an oscilloscope.
The surge when a computer is first turned on I fully understand and the start of an export run will add a lot of additional GPU activity to what is already going on, i.e. the 5900X and the 5700X are both CPUs without an onboard GPU so there is always some background GPU activity.
Even with only export worker started the increase in activity can go as high as 300W (just tested) but with a well engineered PSU neither the machine power on nor the surge when the the GPU goes from mostly idling to full on should have a deleterious effect on the PSU.
I do not believe that the overall power of the PSU is the defining factor providing the power required does not exceed the rated capacity of course.
The 400W that I am seeing on the external power meter should be possible to accommodate with a 500W power supply but I have added a table to the bottom of this post which might be useful and additional factors need to be considered, i.e. any future upgrades in particular.
The design of the PSU will be that defining factor and the original PSU that was fitted to @Martin1958’s computer was failing from time to time because either the design was inadequate or, more likely, a component was simply not able to cope.
I ran my 5900X with an RTX 3060 for a number of months with a Seasonic 550W PSU doing export tests without a single hiccup, or rather there were hiccups but they were of DxO’s software making not my hardware.
Currently the power meter is not going above 400W during a 5 worker export test but as I also confirmed, the price jump between 650W and 850W for the brand I showed was small. Unfortunately for me, with the model and brand I use, when they were available, the price difference was considerable.
However, I found the following table on an MSI site with recommended PSU ratings which might be useful. It is available here https://www.msi.com/blog/recommended-psu-table and was published in January 2023
