Corsair RMi-850w , default 12V rail OCP setting ?

[ehume]

Transient spikes can get higher than that, but you need a faster meter to see those spikes.

But will transient spikes last long enough to set off the OCP?

[Mezoxin]

according to my very limited knowledge , I think so as these are electronic overcurrent protection circuits which may take down to 10ms to respond , the fuse (Thrmal enrgy) and circuit breakers (EMF) though take a much longer time about 0.1s

[Tator Tot]

But will transient spikes last long enough to set off the OCP?

They can, yes. This was the problem that Seasonic Focus units had, where GPUs with high transient loads would tripper OCP and cause the units to shut down.

[Mezoxin]

How so ? the focus plus is single rail , its ocp is set at the maximum amperage the PSU can handle , no gpu would ever reach that value on a focus plus 650 850 or 1000 w

[Mezoxin]

I have found this statement presumably by seasonic on reddit

''AMD's Vega 56/64 graphics card has a very high transient power consumption. The oscilloscope screenshot below shows the transient current when using the two Vega 56 CrossFire for FurMark test, up to 102A / 10ms, which means the power supply must withstand 1200W peak wattage. Even a single Vega 56 graphics card may have nearly 600W of transient power consumption.

file-Af5QnaoIYo.jpg
In this case, from the security point of view, in order to protect other parts of the computer including the graphics card, the overcurrent protection threshold and trigger time of some FOCUS PLUS power supplies are set relatively sensitive. After the power supply taking protective measures, the computer may restart or shutdown.
AMD officially recommends 650W/750W power supply for Vega 56/64. Basically, only users who use FOCUS PLUS 550 can possibly encounter such power overload problems. If the user's power supply is purchased before January 2018 (according to the serial number on the power sticker), please contact Seasonic Customer Service for after-sales service.
A power supply sold after January 2018 has the updated sensitivity preset of overcurrent protection, so users can use it with confidence.
If you are using a high-power water-cooled Vega graphics card or other high-end graphics cards, please purchase power supplies with higher power ratings to ensure that the computer works properly.
In rare cases, using FOCUS PLUS and ASUS GTX970 STRIX graphics cards may result in continual black screens, which is currently only present when paired with the ASUS GTX970 STRIX model. Using the PCIe power cable without capacitors can solve the problem. If the user encounters such problems, he can contact customer service to obtain a PCIe power cables.
We have been cooperating with major graphics card manufacturers to solve the problems caused by the increasing power consumption of graphics cards.''

I never knew that transient loads can get that high

[ehume]

100 Amps is a lot of current. It is surprising that a card would draw so much, especially because the wires and connectors are not rated -- even in extremis -- to carry so much current.