PSU Wattage: First Time Build

[lilith002]

System Build
Intel i7 8700K / Asus ROG Strix Z370-I / 16GB / EVGA GTX 1080 SC ACX 3.0 / m.2 WD Blue 500GB SSD & WD Caviar Blue 7.2K 1TB HDD / NZXT X52 Kracken AIO / NZXT H200i ITX Case / EVGA G3

GPU - Factory over-clocked
CPU - No current over-clock
PSU Brand/Model - EVGA G3 Modular
TDP: 344 (pcpartpicker)

While I am still deciding on which PSU wattage to purchse and will take suggestions, I would also like to understand PSU's a little better. I know about the 12V and such, so I'm wanting to find which wattage will be most efficient for my build.

Rough number for CPU, GPU, and Motherboard Combined Power Consumption
Idle: 62W
Gaming: 273W
Stress: 525W
Overclock: ?

From my understanding;
550W, 80+, 20% (Load) / 87% (Efficiency), 50% / 90%, 100% / 87%
Load: 110W (20%), 275W (50%), 550W (100%)
Power Draw: 126.43W (20% / 87%), 305.55W (50% / 90%), [strike]632.18W ( 100% / 87% / Stress)[/strike]

 

[Rexper]

so I'm wanting to find which wattage will be most efficient for my build.

Choose wattage that can provide the necessary consumption. If efficiency is a concern choose an efficient PSU. Don't confuse the two; trying to relate wattage and efficiency will only mislead you.

If at worst case power consumption, 525W

That is likely TDP values when at the worst scenario if not way over estimated, which won't ever occur in your PC.

525W is near 100% load on the 550W PSU meaning power draw would be well over 550W.

For the most part the PSU doesn't care how much power it takes it, only how much it delivers. Since some power is lost as heat in the PSU, it has to compensate by consuming more from the wall to deliver the required power.

A power supply rated for 550w should be able to deliver 550w even if it is consuming 630w from the wall. And good power supplies like yours are rated to work at 100% power so even if your PC did consume that much it wouldn't be an issue.

The EVGA 550 G3 is fine. Enough wattage and high quality PSU. If you want an efficient power supply I suggest the Cybenetics Efficiency ratings as a guide: https://www.cybenetics.com/index.php?option=power-supplies

 

[lilith002]

Choose wattage that can provide the necessary consumption. If efficiency is a concern choose an efficient PSU. Don't confuse the two; trying to relate wattage and efficiency will only mislead you.

Indeed, they are different things. But the load to PSU wattage and efficiency does vary, at least according to the 80+ rating chart. And I've read things such as quieter operation and better overall effiency with a higher PSU wattage.

That is likely TDP values when at the worst scenario if not way over estimated, which won't ever occur in your PC.

The numbers I used came from idle, gaming, stress and torture tests posted by Tom's Hardware for CPU, GPU, and Motherboard.

A power supply rated for 550w should be able to deliver 550w even if it is consuming 630w from the wall. And good power supplies like yours are rated to work at 100% power so even if your PC did consume that much it wouldn't be an issue.

True, I thought surpassing the PSU wattage was a bad thing. Mixed up power draw being higher with component load being higher than the PSU wattage which is a bad thing.

The EVGA 550 G3 is fine. Enough wattage and high quality PSU. If you want an efficient power supply I suggest the Cybenetics Efficiency ratings as a guide: https://www.cybenetics.com/index.php?option=power-supplies

That is okay with the stock over-clocked GPU, room for upgrades aging of parts, possible over-clock of CPU --likely I would not leave the CPU over-clocked, but would use it as hands on learning --

Thank you for the link and info. Having the best efficiency overall in important to me. The EVGA is good, but it looks like I might be able to do a bit better.

 

[Rexper]

And I've read things such as quieter operation and better overall effiency with a higher PSU wattage.

Whatever you read is someone that doesn't understand power supplies.
Efficiency will not be better overall with higher wattage because your load is never constant. Also, higher wattage power supplies usually are less efficient at idle loads, which do add up. I've looked at a few different PSU series from the Cybenetic Database, comparing how it affects your power bill, and what I can say is that wattage makes a negligible difference. Sometimes you slightly save money, sometimes you lose money.
An overall more efficient PSU model/series will make a difference, not wattage.

And noise, most of the time, is louder with a higher wattage PSU from the same series. Because the higher wattage PSUs need a higher performing/faster fan to cool down at higher loads. The EVGA G3 series is an example.

Your power consumption would always stay under 400w, that PSU is fine. At load your system would average in between 250 and 300w.

If efficiency is very important to you, you may want to reconsider overclocking too.

 

[lilith002]

An overall more efficient PSU model/series will make a difference, not wattage.

I figured it out, they were talking of certain features with the specific PSU and not overall efficiency. I know PSU wattage itself won't increase efficiency, but what I was looking for was the load wattage in relation to the PSU wattage that gave the best efficiency which according to the table is 50% of the PSU wattage with PSU wattage just serving as a base for calculations. Otherwise, yes, increased PSU wattage means higher overall consumption and "loss" to heat.

Your power consumption would always stay under 400w, that PSU is fine. At load your system would average in between 250 and 300w.

Yes, even at stress levels the power demand would be under the 550W specification, but only just. That was my concern due to the numbers I got from Tom's Hardware stress and torture tests and reviews. The 650W recommendation came from the guide offered on Linus Tech Tips giving the 650W for a single GPU over-clocked build.

The PC will mostly be used for word processing and gaming at high quality from time to time, so when I say best efficiency I mean for the operating load to be close to the highest efficiency point of the PSU

If efficiency is very important to you, you may want to reconsider overclocking too.

True, but the aim of over-clocking is testing and learning. I wouldn't keep the CPU over-clocked. I'm thinking to jump down to the i5 8600K -- I don't need the threading and use the saved cash for a platinum PSU.

For a 1080ti build, what PSU wattage would you recommend? I see the build guides on pcpartpicker and they all have 650W.

 

[R0GG]

I Think a 650 watt PSU would be a good fit for your system with a good margin of power for overclocking, preferably all modular, Seasonic or corsair brand:
- Seasonic FOCUS Plus Series SSR-650FX 650W 80+ Gold >> https://www.newegg.com/Product/Product.aspx?Item=N82E16817151186
- CORSAIR RM650X 2018 CP-9020178-NA 650W ATX12V / EPS12V 80 PLUS GOLD >> https://www.newegg.com/Product/Product.aspx?Item=N82E16817139232

 

[Rexper]

550w is more than enough. Your system will not use over 450w likely ever.

A 650w PSU has zero benefits. You’ll only lose money, end up with a louder psu, and have more damage in an event of a fault.

Relative PSU load in relation to efficiency won’t make a difference in the end. Just get the best psu in your budget at 550w.

 

[lilith002]

I Think a 650 watt PSU would be a good fit for your system with a good margin of power for overclocking, preferably all modular, Seasonic or corsair brand:
- Seasonic FOCUS Plus Series SSR-650FX 650W 80+ Gold >> https://www.newegg.com/Product/Product.aspx?Item=N82E16817151186
- CORSAIR RM650X 2018 CP-9020178-NA 650W ATX12V / EPS12V 80 PLUS GOLD >> https://www.newegg.com/Product/Product.aspx?Item=N82E16817139232

Thank you for the reply. Your suggestion and recommendations are appreciated.

550w is more than enough. Your system will not use over 450w likely ever.

A 650w PSU has zero benefits. You’ll only lose money, end up with a louder psu, and have more damage in an event of a fault.

Relative PSU load in relation to efficiency won’t make a difference in the end. Just get the best psu in your budget at 550w.

While I do appreciate the information that you have shared with me, I must be honest with some feedback and say that I do not appreciate replies that come across as curt. I conceded your point on wattage and mention that what I read was talking about the benefit of the specific PSU unit at a higher wattage, not any benefit of higher wattage alone. There is no need to repeat information multiple times and then end a discussion by telling me what I should "just" do, especially when I mention in the OP that I am looking for learn more about PSU

Thank you for the help that you have offered, but I need to move on. And I do hope my feedback is accepted as good natured as it is such.