Which PSU?

[Dawelio]

Heya guys,

So I’ll be honest here, I suck quite bad when it comes to PSUs etc and always kinda goes overkill with them in terms of wattage.

I’m wondering if an Corsair SF600 will be enough or if I should go with the newer SF750? Will those 150W do any difference, in terms of like an 1000W PSU will most likely stay quiet longer than for example an 750W one. Or is this just BS?...

Parts in short: i9 9900K, ASUS 1080 Ti Strix, 32GB 3200MHz memory, 1 x Samsung 970 EVO M.2.

Thanks,
Dawelio

 

[trawetSluaP]

Personally would always want more than I need than be left short.

I also read - and I'm not sure how accurate it is... But PSU's are supposedly at there most efficient around half load so you'd want some headroom anyway if that's the case.

Also means if you upgrade in the future or add hardware you may not need to upgrade the PSU.

 

[grec]

Peak efficiency is usually between 50% and 75% load though that varies somewhat.

The 1080Ti usually has a 250W hard limit, the 9900K + chipset will peak at about 200W, the consumption from the fans will probably be the next big difference after that assuming no water cooling pumps or stacks of drives or anything, but the rest of your system is unlikely to consume more than 50W, bringing you to about 500W under full load, or about 83% of a 600W capacity, but note most of the time gaming is closer to around 60-80% load, so most of the time you'd expect to be pulling closer to 300-400W(50-70%) in "heavy" use. So a 600W PSU should have comfortably enough headroom to keep you in its efficient area through most operation(Bearing in mind efficiency drops off again as you go down below 40 and towards 20% and 0%). The efficiency of the PSU is usually more important to when fan spins up than the rating but if a high rating will keep you in a more efficient range that'd help too.

 

[Eddie long]

You could always use something like bequite's psu calculator on there web site to get an idea , not sure how good it is or how accurate

 

[Dawelio]

Peak efficiency is usually between 50% and 75% load though that varies somewhat.

The 1080Ti usually has a 250W hard limit, the 9900K + chipset will peak at about 200W, the consumption from the fans will probably be the next big difference after that assuming no water cooling pumps or stacks of drives or anything, but the rest of your system is unlikely to consume more than 50W, bringing you to about 500W under full load, or about 83% of a 600W capacity, but note most of the time gaming is closer to around 60-80% load, so most of the time you'd expect to be pulling closer to 300-400W(50-70%) in "heavy" use. So a 600W PSU should have comfortably enough headroom to keep you in its efficient area through most operation(Bearing in mind efficiency drops off again as you go down below 40 and towards 20% and 0%). The efficiency of the PSU is usually more important to when fan spins up than the rating but if a high rating will keep you in a more efficient range that'd help too.

Both PSUs in question are from Corsair and are Platinum rated. No fans or anything in the system, orher than the components mentioned. Perhaps 1 fan, but nothing more than that as the case is the tiny NCASE M1.

 

[grec]

Platinum rated PSUs only vary by 3% efficiency between 20% and 100% load if to the limits so it's less of a concern there, to be honest if you wanted a 2nd GPU you'd probably want 850W to have the same margin so I don't think the extra 150W margin of a 750 would be of any benefit, realistically you can't get GPUs that consume more than 300W on their own in normal operations so any single-GPU upgrade will be fine with the 600W and any multi-GPU upgrade would probably need more than the 750W. Similarly, with tthe CPU, unless you switch to a HEDT socket you're not going to find many more chips that need the ~160W peak of the 9900K.

 

[NeverBackDown]

You could get away with the 600. 750 is a safer bet if you plan on overclocking.

You could run a similar system with a 1080 and still do fine with a 450watt PSU if you wanted(it's been done and it's safe). 1080ti won't consume much more.

If it's a big price difference, get the 600. If like 10-20 more get the 750.

 

[Dawelio]

Hope you guys don’t mind me resurrecting my old thread, since thought making a new one was a bit pointless...

A mate of mine asked me a question regarding PSUs, now as my OP post in this thread, I don’t feel I’m that qualified to answer his questions really, so asking here instead.

Probably a dumb question to some of you, by logic and all, but asking anyway...

So he has an Corsair RM1000x PSU, but has always been a bit of an ”bragging rights” type of person. So he has started looking into the Corsair AX850 (V2) instead, since it’s Titanium rated and his RM is ”just” Gold.
Although, at the moment, the AX1000 cost a cent less than the AX850... So he’s wondering if he shall go for it.

What I’m thinking though is how much will he gain really? From his RM1000x that scored a perfect 10 on JonnyGuru and he even praised it for surpassing Platinum rating in his tests.

He also wonders regarding the whole 1000W won’t run as hard and therefore as hot, as an 850W and therefore will be cooler and run quieter. Now, even though this sounds logical, I’m not so sure if the real world scenario really is that ”simple”

So what do you guys think about all of this? He’s mostly interested in thoughts regarding the last 2 points... Regarding higher wattage meaning less heat and less noise?.

Thanks all and apologies again for resurrecting my old thread.

Regards,
Dawelio

 

[NeverBackDown]

Literally all he's doing is having a smaller power supply.

 

[SuB]

Having more headroom (so having the 1000w) = the fans will stay off for more time (especially on an RM) and will run quieter and cooler overall,.

Having less watts (850w) = driving that harder = probably more noise...

It really is mostly that simple, you're correct.

 

[AlienALX]

Is 600w even enough for a 9900k and 1080ti?

That may cut it close.

 

[SuB]

Is 600w even enough for a 9900k and 1080ti?

That may cut it close.

850w*

 

[grec]

[TL;DR: A Titanium PSU will output almost half the heat of a Gold rated PSU(~6% of draw as heat vs 10%) most of the time and therefore should require less active cooling.]

Having more headroom (so having the 1000w) = the fans will stay off for more time (especially on an RM) and will run quieter and cooler overall,.

Having less watts (850w) = driving that harder = probably more noise...

It really is mostly that simple, you're correct.

Well, sort of, a higher rated PSU should be have better cooling to match, but the noise is a result of moving the waste heat energy, the waste heat energy is calculated from the efficiency. A titanium 850W PSU should be 4% more efficient in the main power band(40-60% load), with that rising to 5% just beyond that, and critically any PSU below a Titanium doesn't have an efficiency certified for idle or heavy loads, so that gap could widen further outside of 25-75% load. For a Gold rated PSU you typically see curves like this(Image from Corsair):

I know 4-6% efficiency might not sound like a lot, but if you're pulling 600W that's ~25W of heat (Titanium 230V peak eff.) vs ~50W(Gold 230V peak eff.), which very well could be the difference between fans spinning or not, and remembering peak efficiency is the best case scenario of comparison for the Gold PSU(Though ofc at lower wattages the absolute gap shrinks even if the %age eff. widens).

Using an overspec'd PSU also harms efficiency in itself(Though ofc so does using a heavily underspec'd one), if they're not in that 25%+ load gap most of the time(And it's very rare your PC would draw 250W+ unless under notable load), then their PSU won't be running to a rated efficiency at all with a Gold, while with the 850W Titanium it'd be in its rated efficiency range as low as 85W. Assuming they rarely go over 750W load (Which would take some serious overclocking with those parts, remembering this is not load at the wall we're worrying about which is typically 10-20% higher, those parts would probably have an internal draw of about 500W while gaming) the Titanium 850W should be roundly more efficient and therefore quieter assuming roughly equivalent fans & internal dissipation rate.

 

[Dawelio]

Having more headroom (so having the 1000w) = the fans will stay off for more time (especially on an RM) and will run quieter and cooler overall

Really? Would think the opposite - that an higher rated PSU would do it better, ie the AX (Titanium) over the RM (Gold).