Running a high power PSU with low power system?

[joshwa]

Online I'm always reading "is this enough for my system" where people have super high end systems (fast CPUs, massive graphics cards etc) and they *need* 800+ watt power supplies...

But I'm more interested in the other end, low power systems. So, of course I can run a low end system (i5-4460t 35W 1 sdd, 1hdd) on a low power psu like a 300w FSP (gold)... But what if I use an 850w PSU (like a Corsair RM850x) with a passive fan design?

Is this bad for the psu? Which one will be more efficient?

Just wondering if there's any benefit? (silent operation is one immediate benefit).

Thanks
Josh

[Rob_B]

It's fine, maybe not as efficient as the PSU can do but it'll likely just sit happily in passive mode

See here for the rm850x (3rd gen) efficiency at different loads, for example @ 100W it's about 90%, at 450W its 92%, so not a massive difference - https://www.kitguru.net/components/powe ... -review/5/

[Saracen]

With the caveat that I'm no expert, I'd agree with Rob, above. I've long held the view that PSU is an easy place to economise and that it's courting potential disaster to do so. I'm pretty fussy about what PSUs I'll use ... and about some "ratings".

I'd say you won't quite get maximum efficiency (as in ratio between mains power in, and internal power out) with an overly large PSU and maybe that was an issue many years ago. But with a good quality, modern PSU while it might cost you a tiny bit more on your 'leccy bill to beef up, because it's not drawing at the optimum point, I think it'll be a tivial amount and, personally and within reason I'd rather over-spec the PSU, in part because a good PSU should last through several upgrades, so if you do shift to more powerful (and power hungry) CPU or GPU (or both) you'll be ready without having to buy a new PSU. Just don't get a 2kW beast "just in case" when you currently ('xcuse pun) only need about 450W.

As I said, not an expert, but that's what I'd do - I'd get the best quality PSU I could afford, without going totally silly, and build in some leeway for later.