PSU Test how much do you need.

[G-RFRY 1,707]

 

[vortex681 806]

Sorry, didn't watch all of the video but the other things to bear in mind are that most power supplies are most efficient at about 50% capacity. Also, my 850W PSU remains passive (hence very quiet) at all times as the temp never gets high enough to trigger the fan. Running a 400W PSU with a system that uses most of that power will inevitably lead to higher temps and a potentially shorter PSU life.

[G-RFRY 1,707]

37 minutes ago, vortex681 said:

Sorry, didn't watch all of the video but the other things to bear in mind are that most power supplies are most efficient at about 50% capacity. Also, my 850W PSU remains passive (hence very quiet) at all times as the temp never gets high enough to trigger the fan. Running a 400W PSU with a system that uses most of that power will inevitably lead to higher temps and a potentially shorter PSU life.

But if you watch it all it`s not the power rating but the stability most users go OTT, most custom gaming Builds come with a 650W PSU even with SLI. 

This is relevant at the moment as i have seen some think they will need a 1000W PSU for the 3090 GPU, not so the 3000 Series uses a smaller die more efficient. 

[vortex681 806]

I agree - 1000W or more is a complete overkill for a the average gaming rig.

[Bob Scott 7,715]

I shoot for a 50-100% overbuild.  In a high quality PSU that means it comes with better IC heatsinks, higher-rated switching diodes, and (usually) better filtering.  The price differential, especially on the lower power units from 500-800W, is pretty small.

Some things have changed over time...the heavy initial current draw experienced during HDD spinup is largely gone...most systems now have only one HDD, if any at all.  Multi-GPU configs are fading away, too.  On the other side of the equation, an overclocked 10-core 10900K can dissipate well over 250W, and the fastest of the next gen of GPUs are rumored to be somewhere in the 300W range.  Other possible significant loads to consider are water cooling pumps and extra fans.

In the overkill dept, I have an EVGA 1600W PSU sitting in my spares bin...picked it up as part of a package deal back when I bought two 1080Ti GPUs for an SLI build.  It's a real beast.

[martin-w 3,234]

2 hours ago, vortex681 said:

Sorry, didn't watch all of the video but the other things to bear in mind are that most power supplies are most efficient at about 50% capacity. 

 

True, but even modern  Gold PSU's are still highly efficient at higher loads. The EVGA 850 Gold for example has a max efficiency of 96% but even at 800 watts it only drops to 90%.

So yes, what you say is true, but nobody should be concerned about their power bill if their PSU will be running above the point of peak efficiency. And for longevity, quality PSU makes have a warranty of 10 years or more.

But yes, I too tend to spec higher than minimum requirement. Primarily because a few hundred extra watts is not much dearer. And of course you have that spare capacity for future proofing.

 

 

Edited September 1, 2020 by martin-w

[micstatic 4,313]

I would argue a 850 will be fine for the 3090.  However I've ordered a 1000w.  For a few reasons.  

-Most efficient around 50-60% usage.  I have an over clocked 9700k, will have a 3090, 32gb ram.  Eventually 64.  7-8 USB connections.  2 M2's.  2 7200 HDD, 3 screens connected.  1 skalarki mcdu/fcu connected.  Multiple case fans, a liquid cooling system...  I'm going to guess that brings me to a usage of potentially 700w or slightly under with the 3090.  So the headroom at 1000w is good for efficiency and also good for whatever my next mb/cpu combo is.  

[Bob Scott 7,715]

After a cursory look at coverage of the nVidia Ampere announcement today, I think a 1000W PSU doesn't look anything like overkill in an overclocked 8+ core system with a 3090.

I also suspect a good number of folks eyeballing those Ampere boards haven't yet stopped to consider how their UPS will handle a computer drawing 700+ watts under load.

[Ixoye 1,812]

I can highly recommend Phanteks Revolt Pro 850W, (Seasonic) it is fully modulated and have 6 separate CPU/PCI slots, it also allows you to connect a secondary power supply if needed, there is also a 1000w version available.

 

[vortex681 806]

7 hours ago, w6kd said:

After a cursory look at coverage of the nVidia Ampere announcement today, I think a 1000W PSU doesn't look anything like overkill in an overclocked 8+ core system with a 3090.

In their testing, the maximum power usage that Gamers Nexus had was 537W with the 10900k and a 2080ti. The RTX 3090 will supposedly have a TGP of 350W which is only 30W more than the 2080ti - that would still keep the total system power below 600W. Based on that, a 1000W PSU does still look like a bit of an overkill for most people.

[Bob Scott 7,715]

1 hour ago, vortex681 said:

In their testing, the maximum power usage that Gamers Nexus had was 537W with the 10900k and a 2080ti. The RTX 3090 will supposedly have a TGP of 350W which is only 30W more than the 2080ti - that would still keep the total system power below 600W. Based on that, a 1000W PSU does still look like a bit of an overkill for most people.

Note that the test was done with the CPU/GPU at stock speeds, no overclocking.  About 8 min in he talks about the difference between long and short-duration testing, the difference being due to the stock intel Turbo Boost 3.0 reducing the multiplier after around a minute of heavy load on the stock 10900K.  Now override the stock turbo boost schedule and crank up the voltage and mults on all 10 cores to 5.1 GHz or more.  Then bump up the GPU clock and voltage (or maybe the OEM already has).  And then add a Laing D5 water pump and a couple extra fans on the radiator or case. 

I think "most people" that spring for a 9900K or 10900K are overclocking their CPUs, so this isn't just a fringe case analysis.

I don't trust that the engineering guys in a competitive retail environment are building in very much of a safety factor above the rated capacity.  A catastrophic failure in a PSU can take the entire computer with it, so I prefer to keep a healthy known margin between actual power load and rated capacity.

[martin-w 3,234]

2 hours ago, w6kd said:

A catastrophic failure in a PSU can take the entire computer with it, so I prefer to keep a healthy known margin between actual power load and rated capacity.

 

I'm not sure about the "entire" computer but a failed PSU can certainly damage other components. That often happens when the PSU short circuit protection fails and the wires that run to the short act as a resistor. When that happens OCP (Over Current Protection) fails and power just keeps getting fed down the line. That's when you end up with  damaged components and even melted wires. Doesn't happen with multi rail PSU's of course, because OCP on each rail is set much lower.  Nice thing about the higher end Corsair PSU's is that you can switch from multi rail to single rail. set up your PC in multi-rail and if all is running well switch to single rail in the software.

But as I say, in many years of building PC's and after having quite a few PSU's fail, I never had one take out the "entire" Computer. 

 

Edited September 2, 2020 by martin-w

[vortex681 806]

3 hours ago, w6kd said:

I think "most people" that spring for a 9900K or 10900K are overclocking their CPUs, so this isn't just a fringe case analysis.

I disagree, but there's no way to know for certain. They're certainly enthusiast CPUs but that doesn't automatically mean that most people who buy them will want to push them to their limits. I would guess (and that's obviously all it is) that mild overclocks are much more common than massive, custom loop-cooled ones. People buy high-end CPUs because, even at stock speeds, they will out-perform most other CPUs. My experience with overclocking has been that whilst you obviously gain performance, in my opinion it's rarely significant enough to risk the stability or longevity of the CPU or GPU. As I don't have unlimited funds, If I make a big investment in components I want them to last as long as possible. If I get smooth performance at stock speeds, that's generally were I've tended to end up after experimenting.

Edited September 2, 2020 by vortex681

[CallsignDE 37]

i7-10700k + GTX3080

What do you guys think? Will 750w be enough or better get a 850w one?

[Tektolnes 184]

750w should be fine but I'd probably go for the 850w just to have a bit more space and room for additions down the line.