Understanding Monitor Response Time at Different Refresh Rates

[flipped_bit]

I have been shopping for a 1440p 144Hz monitor for PC use only for a long time now, and have been reading a lot of rtings.com reviews (in addition to watching videos from LTT, Hardware Unboxed, etc.).  

 

On a rtings review, they test response time at both the max refresh rate and at 60Hz.  Invariably, the response time is lower at 60Hz.  

 

The question I can't find a clear answer to - even on rtings site - is under what conditions will a monitor run at 60Hz, and therefore have a lower response time?  I understand hooking up a 60Hz source like a console is one situation.  I will be using this monitor with only a PC source, so I want to know whether there are any circumstances where my PC would change from a max (144Hz+) signal to a 60Hz signal.  

 

Here are a couple hypotheticals - curious as to which response time would apply to each.  For each hypothetical, the refresh rate would be set to max in the OS and in-game FPS would be at 60

 

- VRR OFF. 

 

- VRR ON.  

 

- Game engine limits max FPS to 60.  VRR OFF.

 

- Game enforces vertical sync and max FPS of 60.  VRR OFF.

 

The reason this is important is because a) I want a good response time experience across a broad FPS range, and b) very few monitors have great response time at 60Hz, so if I only have to care about the response at high refresh rates (as this is for PC use only) this greatly widens the range of monitors I can consider.

 

I'd really appreciate some input into this - thank you in advance.  

[Stahlmann]

6 hours ago, flipped_bit said:

I will be using this monitor with only a PC source, so I want to know whether there are any circumstances where my PC would change from a max (144Hz+) signal to a 60Hz signal.  

Basically any time your fps dip below 144Hz and you have VRR enabled, your refresh rate will also change. Not just to 60Hz, but every step in between. For example if your game runs at 92 fps your refresh rate will also be 92Hz.

 

6 hours ago, flipped_bit said:

I- VRR OFF.

Here the 144Hz response time will apply, as the monitor always runs at 144Hz without VRR.

 

6 hours ago, flipped_bit said:

- VRR ON. 

Here the CURRENT refresh rate applies, which will be the same as your CURRENT fps. For example with VRR enabled and running at 60fps will result in the 60Hz response times.

 

6 hours ago, flipped_bit said:

- Game engine limits max FPS to 60.  VRR OFF.

The 144Hz response times will apply, but running your refresh rate and fps out of sync will result in the usual non-VRR issues. For example tearing and stuttering.

 

6 hours ago, flipped_bit said:

- Game enforces vertical sync and max FPS of 60.  VRR OFF.

This is the same as the one above. 144Hz response times will apply, but with the same downsides of not using VRR, plus the added input lag from Vsync.

 

6 hours ago, flipped_bit said:

The reason this is important is because a) I want a good response time experience across a broad FPS range, and b) very few monitors have great response time at 60Hz, so if I only have to care about the response at high refresh rates (as this is for PC use only) this greatly widens the range of monitors I can consider.

Response times at 60Hz are not as important as you'd think imo. Games that run on locked at 60Hz typically don't need the lowest possible input lag. But like i said above, these response times also apply when using VRR and your fps dip in the 60's. So if 60Hz response times matter to you specifically depends on the games you play and the hardware power you have. If you can comfortably run all your games at 100+ fps then 60Hz response times don't really matter for you. But i'd personally always go for a monitor that has 1 overdrive mode that can be used at ALL refresh rates without having big performance issues at a specific range. But this feature is typically reserved for higher-end monitors (with a few exceptions).

[flipped_bit]

Great response Stahlmann, thank you.

 

Quote

But i'd personally always go for a monitor that has 1 overdrive mode that can be used at ALL refresh rates without having big performance issues at a specific range. 

Agreed.  Unfortunately it seems like there are very few such monitors on the market.  The Dell S2721DGF seems to be one, but the reports of eye strain have steered me clear until now.  It is on sale though...

[Stahlmann]

9 minutes ago, flipped_bit said:

Great response Stahlmann, thank you.

 

Agreed.  Unfortunately it seems like there are very few such monitors on the market.  The Dell S2721DGF seems to be one, but the reports of eye strain have steered me clear until now.  It is on sale though...

There are a few monitors that can do it: The LG 27XX850-B models, the MSI MAG274QRF-QD come to mind right now. If i'd think about it some more i could find more.

 

To be clear: These monitors don't always the the "optimal" single overdrive experience. the important thing is that it doesn't get too bad when you're hitting lower refresh rates. It's still possible that the monitor has a better mode for 60Hz specifically, but at long as the optimal 144Hz mode is still acceptable for 60Hz then it's a single overdrive mode experience imo.