How to tell when PSU needs upgrading?

[martincmartin]

Suppose I install a new, more powerful graphics card. I'm not sure whether my existing power supply is powerful enough. How can I tell whether I should upgrade my PSU?

Do I look in the "GPU Performance Limiters"? If "Power" is the limit, does that mean my PSU isn't providing enough power? What if "Power" is the limit, combined with "Total GPU Power [% of TDP]" being less than 100%?

Or will the GPU beep or refuse to boot?

 

[martincmartin]

In other words: Is CPU and/or GPU power throttling a thing for under powered power supplies? If so, is there some indication in HWiNFO that tells me when it's happening, so I can go out and buy a new PSU?

 

[Martin]

Do I look in the "GPU Performance Limiters"?

No, that's not the right indicator for such case.

Best is to watch the +12V rail how it drops under load. When it drops below approximately 11.5 V then the PSU might not be sufficient.
If the issue is more serious, you'll experience crashes, reboots or BSODs.

 

[martincmartin]

No, that's not the right indicator for such case.

Best is to watch the +12V rail how it drops under load. When it drops below approximately 11.5 V then the PSU might not be sufficient.
If the issue is more serious, you'll experience crashes, reboots or BSODs.

Thanks a lot! Is it worth having some sort of alarm or pop up, or other indication, when the +12V rail drops below 11.5V?

 

[Zach]

Thanks a lot! Is it worth having some sort of alarm or pop up, or other indication, when the +12V rail drops below 11.5V?

Yes of course you can set an alarm at 11.6~11.7V
Doesn't have to be 11.5V

Just curious, what is your system specs in detail and your PSU, and what GPU are you thinking of getting?

 

[martincmartin]

Thanks! I'll look into how to set up that alarm.

I have a RTX 4080 Super, and nVidia recommends an 850W power supply, but mine is a Corsair RM750x. I don't have much else that takes power, my CPU is an i5-14600 that isn't overclocked. So I think I'm fine with the 750W PSU, but wanted to use HWiNFO just to be sure.

 

[Zach]

850W for a 4080S is too much. nVidia exaggerates a bit on power here.

Nothing to worry about...
A 4080S is consuming around ~320W at max with transient very short spikes no more than 370~380W

320W + 200W for the rest of the system it gets you to 500~550W.
Even with the short spikes added, total max power cant be over 600~620W. Still plenty until 750W

My estimation is that your system during gaming will be on average about 450~500W with spikes no more than 600W.
Should be totally fine if your PSU is still healthy.







Use HWiNFO to monitor GPU+CPU total average power

Look at screenshot below
Its ~3hours of game play

My CPU+GPU add around 430W by avg, and the total avg system is ~500W with spikes at 600+W
My PSU is also a 750W and fortunately has total system power monitoring (PSU output).

 

[martincmartin]

Thank you for the very detailed info! I very much appreciate it.