Question Which PSU makes sense for this build, given overclocking?

Aug 4, 2019
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If I am going for:

-x570 motherboard
-3950x CPU
-64 GB RAM @ 3600 MHz at 16CAS
-2080 TI overclocked
-2 TB PCIe 4.0 NVME SSD
-Roughly 5-7 USB devices in use
-Custom loop for cooling CPU and GPU
-27" monitor, gaming at 1440p 144Hz, possibly 30"

Basically what would be the max power consumption of this build if I were to run everything at max load, overclocked?

I am trying to gauge what kind of PSU would be appropriate for this
 

Aeacus

Glorious
Herald
Let's see: GTX 2080 Ti is 260W, R9-3950X is 105W, rest of the system is about 150W, open loop about 50W or so. Making the total about 465W. Add the OC to it, which can put another 100W or so to it and at max load with OC, you'd be looking towards roughly 575W.

Here, 750W PSU would be enough but just in case, i'd go with 850W unit (to give more headroom OC consumption wise). That being said, i suggest looking towards any Seasonic unit in 800W range, e.g: Focus+ 850 (80+ Gold), Focus+ 850 (80+ Platinum), PRIME AirTouch 850 (80+ Gold) or PRIME Ultra 850 (80+ Titanium),
pcpp: https://pcpartpicker.com/products/compare/jWFXsY,P638TW,nyQG3C,6Qx2FT/

Warranty wise:
Focus+: 10 years
PRIME: 12 years (includes all PRIME models: regular, Fanless, AirTouch, SnowSilent, Ultra)

All 3 of my PCs: Skylake, Haswell and AMD are also powered by Seasonic. Full specs with pics in my sig.


Oh, same series 1kW unit compared to 850W unit doesn't have much difference. Only the PSU's efficiency level could be a bit lower since PSU's are most efficient when load on them is between 50% - 80% of their max rated wattage.
 
Thanks. Would 1000W be overkill / would it serve zero benefit over a 850W?
1000 watts would be overkill and there would not be much of a benefit over 850. You may see a few cents off your electric bill annually with the 1000 watt PSU because many PSUs are most efficient at 50% capacity. But it wont hurt anything either. Sometimes with sales the 1000 watt may only be a couple bucks more than the 850.
 
Aug 4, 2019
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The math I did was a little different, piecing together measurements from what I've seen online (or speculations, in the case of the 3950x), as I am trying to estimate the power load at max when overclocking on water.

The 2080 ti when it's flashed and overclocked can pull near-400W, the 3950x could possibly pull as much as 250W when overclocked on full load, the RAM I put at 3W per 8G so 24W total, this x570 mobo has killer vrms so I put it at like 30W (according to the Buildzoid video you could go even higher than this?), custom loop I've seen anything from 20W to 50W so I erred on the high side, PCIe 4.0 M.2 NVMe SSD I put at 10W, fans I put at 1.8W per fan and just rounded up to say 10W.

Adding it all up that's 400 + 250 + 24 + 30 + 50 + 10 + 10 = 774W

And if I want that to be at the 50% efficiency point doesn't that put me near-1500W?

I know this is much much much higher than the usual recs but I want to know where my logic is off.

In the past every time I've taken recs it ends up being underpowered because people assume I am not multitasking as much as I say I am (I game on one monitor and usually have lots of things going on on the other screen, ranging from resource-hungry code on multiple IDEs for all my projects, to video editing, to virtual machines, to Photoshop, to Chrome with lots of tabs to streaming etc).

I want to make sure that even when my computer is cranking away at a high load, there will be more than enough power to run it all efficiently.

How do I better calculate all of this?
 
Last edited:

jankerson

Illustrious
BANNED
The math I did was a little different, piecing together measurements from what I've seen online (or speculations, in the case of the 3950x), as I am trying to estimate the power load at max when overclocking on water.

The 2080 ti when it's flashed and overclocked can pull near-400W, the 3950x could possibly pull as much as 250W when overclocked on full load, the RAM I put at 3W per 8G so 24W total, this x570 mobo has killer vrms so I put it at like 30W (according to the Buildzoid video you could go even higher than this?), custom loop I've seen anything from 20W to 50W so I erred on the high side, PCIe 4.0 M.2 NVMe SSD I put at 10W, fans I put at 1.8W per fan and just rounded up to say 10W.

Adding it all up that's 400 + 250 + 24 + 30 + 50 + 10 + 10 = 774W

And if I want that to be at the 50% efficiency point doesn't that put me near-1500W?

I know this is much much much higher than the usual recs but I want to know where my logic is off.

In the past every time I've taken recs it ends up being underpowered because people assume I am not multitasking as much as I say I am (I game on one monitor and usually have lots of things going on on the other screen, ranging from resource-hungry code on multiple IDEs for all my projects, to video editing, to virtual machines, to Photoshop, to Chrome with lots of tabs to streaming etc).

I want to make sure that even when my computer is cranking away at a high load, there will be more than enough power to run it all efficiently.

How do I better calculate all of this?

750W is fine, just get a good PSU like those that have been recommended.
 
Aug 4, 2019
76
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I understand what's being recommended here, but I am asking what's wrong with my approach specifically so I can understand better rather than blindly rely on say-so.

I'm seeing a lot of contradictory info online depending on where I look so I'm looking for someone to debate those points on their merits.
 

jankerson

Illustrious
BANNED
I understand what's being recommended here, but I am asking what's wrong with my approach specifically so I can understand better rather than blindly rely on say-so.

I'm seeing a lot of contradictory info online depending on where I look so I'm looking for someone to debate those points on their merits.

You don't need to be at the 50% power draw point, that's really bad info.

70% to 80% is fine with GOOD PSU's.

Look at what I am using in my specs below......

Plus the simple fact is you will NEVER hit that 774W power figure using the system, it just won't happen. You will never max out the CPU and GPU power draw at the same time playing games etc, it's impossible.
 
I understand what's being recommended here, but I am asking what's wrong with my approach specifically so I can understand better rather than blindly rely on say-so.

I'm seeing a lot of contradictory info online depending on where I look so I'm looking for someone to debate those points on their merits.
The power draw is not static. It fluctuates pending on the resources being used. The numbers you provided are not really practical in the real world as they are worst case scenarios that wont happen together.

Not every part of your rig is going to be pulling 100% maximum power draw. Even the 400watts you have selected for the 2080ti, that is only going to happen during stress test that put abnormal stress on the GPU. So unless you are planning on video encoding with your CPU while running a sustained stress test on your GPU, you are not going to get wattage that high.

But there is absolutely no harm in running a higher wattage PSU. So if it makes you feel better, then go for a 1000 watt PSU. They dont cost that much more money than a 750/850 watt. But dont go with a 1500 watt PSU, that really is just a waste of money at that point.

Looking at today's prices in the US, you can get a Corsair TXM 750 watt for $100, or a EVGA G2 850 watt for $109, and a EVGA G3 1k watt PSU for $135. All of those are quality PSUs. For a rig that cost as much as the one you are putting together, I would not put too much thought in a $35 difference.
 

Aeacus

Glorious
Herald
The math I did was a little different, piecing together measurements from what I've seen online (or speculations, in the case of the 3950x), as I am trying to estimate the power load at max when overclocking on water.

The 2080 ti when it's flashed and overclocked can pull near-400W, the 3950x could possibly pull as much as 250W when overclocked on full load, the RAM I put at 3W per 8G so 24W total, this x570 mobo has killer vrms so I put it at like 30W (according to the Buildzoid video you could go even higher than this?), custom loop I've seen anything from 20W to 50W so I erred on the high side, PCIe 4.0 M.2 NVMe SSD I put at 10W, fans I put at 1.8W per fan and just rounded up to say 10W.

Adding it all up that's 400 + 250 + 24 + 30 + 50 + 10 + 10 = 774W

And if I want that to be at the 50% efficiency point doesn't that put me near-1500W?

I know this is much much much higher than the usual recs but I want to know where my logic is off.

In the past every time I've taken recs it ends up being underpowered because people assume I am not multitasking as much as I say I am (I game on one monitor and usually have lots of things going on on the other screen, ranging from resource-hungry code on multiple IDEs for all my projects, to video editing, to virtual machines, to Photoshop, to Chrome with lots of tabs to streaming etc).

I want to make sure that even when my computer is cranking away at a high load, there will be more than enough power to run it all efficiently.

How do I better calculate all of this?
The wattage numbers you're adding up for CPU and GPU are peak loads under stress test conditions and as said by many above, i say it again: just because those watts were achieved under lab conditions doesn't mean that you'll also get same power consumption out of them.

I'll run the numbers again:
GPU is 260W, with OC let's put it 360W (adding another 50W to my initial estimation)
CPU is 105W, with OC let's put it 205W (adding another 50W to my initial estimation)
Open loop is 50W
Rest of the system i estimated at 150W but since you dig out exact numbers, it's 74W
Making the total for OCd PC: 689W

Here, as i said above, 850W unit is more than enough, leaving 161W as spare headroom. Even if i were to take your peak wattage number (774W), for 850W PSU, free headroom would be 76W. Also, peak load doesn't continue for minutes or hours. Peak load is only milliseconds in duration which good quality PSU can handle just fine.

Do note that with CPU, it's the luck of silicone lottery. If you get lucky, you'll get CPU which you can OC to e.g 5.2 Ghz. But if you don't get lucky, max OC where your CPU would be stable may be only 4.8 Ghz. Lower OC level doesn't consume as much power as higher OC level. So, there's that.

If you don't believe our expert estimations then you can use online power calculators as well,
link: https://outervision.com/power-supply-calculator

Also, you got the PSU's efficiency wrong. When i said that:"PSU's are most efficient when load on them is between 50% - 80% of their max rated wattage", what it means is that for 850W PSU, it's the most efficient when the load on it is between 425W and 680W. If the load on PSU would be outside of those numbers, PSU's efficiency, at most, would drop 3%.

PSU's efficiency works like so:
850W 80+ Bronze PSU - 20% load (170W) with efficiency of 82% will deliver 170W to components while drawing 200W from the wall. 30W would be wasted as heat.
850W 80+ Gold PSU - 20% load (170W) with efficiency of 87% will deliver 170W to components while drawing 192W from the wall. 22W would be wasted as heat.
850W 80+ Titanium PSU - 20% load (170W) with efficiency of 92% will deliver 170W to components while drawing 183W from the wall. 13W would be wasted as heat.

850W 80+ Bronze PSU - 50% load (425W) with efficiency of 85% will deliver 425W to components while drawing 488W from the wall. 63W would be wasted as heat.
850W 80+ Gold PSU - 50% load (425W) with efficiency of 90% will deliver 425W to components while drawing 467W from the wall. 42W would be wasted as heat.
850W 80+ Titanium PSU - 50% load (425W) with efficiency of 94% will deliver 425W to components while drawing 450W from the wall. 25W would be wasted as heat.
 

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