RM series zero RPM fan mode

[damadok]

Hi

I'm trying to further silence optimize my PC build, and am looking to buy a PSU of the "RM" series. My current build does not use more than 3-400 W at peak performance. I want to maximize the time the fan on the PSU stays off ( refering to the zero RPM fan mode ). On the box it says the fan will start spinning at 40% load. Is this load based on the max output wattage of the PSU, for example 400W if you buy the RM 1000W? Is it, in fact, just a pre-determined temperature, at which the fan starts spinning? Other PSU brands claim their fan starts after a fixed watt consumption, for example 200w. Does the RM series have such a feature?

To summarize, I'm trying to determine what size the PSU should have, if my primary goal is to keep the fan from ever turning on? If it isn't guaranteed that the fan will stay off at peak performance, is it safe to say it will stay off while just browsing, streaming etc perhaps? I don't want to buy a 1000w RM PSU, if it isn't more likely to have the fans turned off, compared to a lower watt RM model.

 

many thanks in advance

[jonnyguru]

The RM series fan starts based on temperature and time (sustained temperature for a given period of time).

 

The 40% load figure is based on the PSU operating in a 25C environment. If your room temp is warmer, the fan will start sooner. If your room is cooler, the fan will start later.

[damadok]

Thanks for the reply.

Does this mean that the fan on a 750 RM and 1000 RM should in theory start at the same time? Or does the bigger PSU develop less heat from sustained 2-300w power drainage? Trying to decide what size the PSU should have.

[jonnyguru]

The 750W is going to start a little earlier because the components under less stress. Remember: the PSU is going to generate heat that adds to the ambient temperature. While the efficiency curves of all of these PSUs is relatively flat, without a fan actively moving the heat out of the PSU hosung, the smaller PSU will heat up exponentially just because of the nature of the parts used.

 

But the fact remains, at the end of the day the PSU's fan is going to start up based on load and time. No PSU has a circuit that actually measures load in the fan controller (unless the PSU is digital, of course). But load is commonly used to illustrate when the fan will start because it's easier to communicate to the average end user.

[damadok]

Thanks for the reply, again.

Yes, I was pretty sure it was temperature/time controlled. I thought there might exist a linear correlation between a given, fixed load on the PSU, and the size of the actual PSU, in terms of heat production. There is an issue of efficiency, too, true. I guess I'll go for the 1000W model and optimize my case cooling, so the RM never starts to sweat ;)