VRAM doesn't downclock with 2 high refresh rate monitors

[chrcoluk]

VRR shouldn't kick in on the Windows desktop anyway. At least my monitor shows constant 144 Hz when I'm not in a game.

I run my monitor at 60hz, I once tried a higher refresh rate and it felt very weird, and also dont see the benefit in it, I would say I only have a high refresh rate monitor as it seems to be the only way to get VRR.

 

[AusWolf]

I run my monitor at 60hz, I once tried a higher refresh rate and it felt very weird, and also dont see the benefit in it, I would say I only have a high refresh rate monitor as it seems to be the only way to get VRR.

To me, it feels a tad nicer when scrolling. Besides, if I keep my desktop at 60 Hz, then my games will run at 60 Hz too, without VRR. So I kind of need 144 Hz for VRR to work properly.

 

[ty_ger]

To me, it feels a tad nicer when scrolling. Besides, if I keep my desktop at 60 Hz, then my games will run at 60 Hz too, without VRR. So I kind of need 144 Hz for VRR to work properly.

AMD GPUs don't have a way to set a separate desktop refresh rate and a separate game refresh rate?

 

[AusWolf]

AMD GPUs don't have a way to set a separate desktop refresh rate and a separate game refresh rate?

They might do, but I can't be asked to set it up for every game individually.

 

[Zach_01]

My display is UW 175Hz OLED.
Had it always at 144Hz.
It’s a G-sync monitor but supports Freesync too.

The 7900XTX was usually idling just below 50W (47-48W) and rarely dropping to 28-30W region.
Always had VRR on from Adrenalin.

Lately I enabled VRR from Win11 display settings also and since the card is idling at 21-23W.

 

[mahanddeem]

From further testing, one 4k monitor at 240hz at 10 bit vram idles at 101mhz with my 4090.
One 1440p active, at 360hz and 10bit color, VRAM clock idles at 50mhz.
When both are active, VRAM clock is at full blast, 1327mhz (which is the FULL 21gbps for the 4090). Evey possible app the uses hardware acceleration is off/disabled. Like Steam, Chrome, etc.
Nvidia Global Profile is set at Normal in Power preference.
I hope Nvidia would investigate this.
I had tagged ManuelG (nvidia development team) at Guru3d to see his response about the matter.

As a temporary solution, I got the habit of disabling 1 monitor if I'm not using both. Lowering refresh rate is (illogical) to say the least to be honest since 1. You paid for an expensive monitor for a high refresh rate 2. Everything is smoother at higher refresh rate even desktop tasks/surfing web and heck even mouse movement 3. You don't get constant switching of refresh rate when launching games 4. It's 2024, last 60hz monitor I ever used was from 2012.

 

[:D:D]

Maybe you could try limiting PStates to P5 / P8 depending on what 40 series uses, to see if there's any adverse effect especially if you have FPS OSD option on your monitors to help check.

For my 3070 P8 runs at up to 810MT/s but measured efficiency is low at less than 60% so about 14.8GB/s bandwidth at 256bit width. P0 reaches around 90%

 

[Vayra86]

2070S has 448.0 GB/s bandwidth, 4070TiS 672.3 GB/s, 50% more and still not enough for 120Hz.

1. I didn't upgrade from 60Hz to downgrade to 60Hz.

2. I didn't buy 3 monitors to just use 2. I could have saved a ton of money by just getting 2 instead.

3. Happens in another machine, both with 2070S and 4070TiS. Didn't test anything below 120Hz, cuz that's unacceptable, since 100Hz monitors cost a lot less than 180/200Hz.

No you don't have 448GB/s. If the memory clocks down, you have fár less. Because bandwidth is a product of memory clock and bus width.

This is also why the GPUs won't clock down as you prefer them to - they need the bandwidth to run said resolution at said refresh rates, and if they have to run varying refresh rates, that adds to the requirement too, because its running two separate resolutions now at two separate refresh rates.

This issue is like @Chomiq said, unfixable. You can at best tweak your way around it by limiting the pressure on bandwidth as described by him.

Or you can buy a stupidly wide card (in the Nvidia stable, all you've got left is an x90 for that now, everything else has abysmal bandwidth with downclocked VRAM) so you can keep it idling more. On my 7900XT (800+GB/s) I barely see memory clock up from 130-200mhz, nowadays, and if it does, its very fine grained, the GPU can even idle at 144hz desktop entirely, using a mere 6W. If I connect a second monitor, it will do so less frequently, but only if I move windows between the two monitors. The lower bandwidth (about 500GB/s) GTX 1080 I had before would clock up more frequently in the same setup.

AMD GPUs don't have a way to set a separate desktop refresh rate and a separate game refresh rate?

I believe AMD GPUs now do a fully automatic and dynamic clocking on the desktop. As in, they will even drop down to sub 10W if there is no activity on screen. I've seen it happen - move the mouse and poof, 19-22W usage. Stop moving for a few seconds, and the GPU apparently goes completely idle, as in, its not doing anything, displaying the image is not taking up continuous power or bandwidth if it doesn't change.

 

[bug]

@Vayra86 Makes you wonder: if nothing is moving on the screen, why send anything to the monitor at all? Something, somewhere, seems to be broken.

 

[Wirko]

@Vayra86 Makes you wonder: if nothing is moving on the screen, why send anything to the monitor at all? Something, somewhere, seems to be broken.

If anything is broken, it's the entire system and standards of video transmission.

The closest thing to sending nothing, in real world desktop monitors, is sending frames at the lower limit of VRR. It's also good if the entire frame buffer fits in the GPU cache, so GDDR can remain idle. (I assume that GPUs use cache for the frame buffer but I've never seen it confirmed).

 

[bug]

If anything is broken, it's the entire system and standards of video transmission.

The closest thing to sending nothing, in real world desktop monitors, is sending frames at the lower limit of VRR. It's also good if the entire frame buffer fits in the GPU cache, so GDDR can remain idle. (I assume that GPUs use cache for the frame buffer but I've never seen it confirmed).

I was more hinting at: https://www.anandtech.com/show/7208/understanding-panel-self-refresh

 

[Vayra86]

@Vayra86 Makes you wonder: if nothing is moving on the screen, why send anything to the monitor at all? Something, somewhere, seems to be broken.

Broken how? The system remains responsive, perhaps the wattage and gpu load reading is off, but other than that? No idea

 

[bug]

Broken how? The system remains responsive, perhaps the wattage and gpu load reading is off, but other than that? No idea

I meant the GPU<->monitor communication implementation is suboptimal. With panel self-refresh, the GPU could almost power-down completely.

 

[Wirko]

I meant the GPU<->monitor communication implementation is suboptimal. With panel self-refresh, the GPU could almost power-down completely.

Panel self-refresh would require some DRAM and some additional logic in the monitor itself. On the other hand, Nvidia is good at idle power saving as it is; TPU's review of the 4080S measured 19 W in two-monitor idle state (but I don't see resolution and Hz specified). Further reduction would be possible by activating VRR in 2D mode (if it's not already active).

AMD is much inferior in that category, their cards regularly have a high consumption and high memory clock in two-monitor idle state. But both companies have more work to do tuning the HW and FW to better scale memory clocks. The clock frequency should adapt to monitor setups that are common with high end cards, but it doesn't, as the OP has found out.

 

[:D:D]

Wasn't there some problem cases with multi-monitor? idr. Maybe clocks are being forced because of that. Unfortunately my dummy plugs are pixel clock limited so cannot reach those high res/refresh rates but as far as scaling it seems to work well for a single monitor but perhaps you don't see this if using software such as GPUZ which displays limited/preferred clocks.

Using effective clock readings with different refresh at 1440p.

Note that core voltage increases at 180Hz.

All these results are shown as 210MHz / 101.3MHz (810MT/s) on GPUZ at PState 8.

Seeing what the cache is doing would be interesting too, especially for that 4090 with lots of L2.

 

[eidairaman1]

Semantics, on with it, typical that clockrates on ram will be higher when 2 or more monitors are attached to 1 card.

Contact nvidia

 

[leppie]

This is a driver issue, not a bandwidth issue.

I noticed yesterday my mem clock was stuck at fullspeed (9501 as per MSI AB).

This was seemingly triggered by turning on HDR on my 4K TV attached to HDMI running 3840x2160 @ 60Hz.

I have 3 other monitors attached all 1440p @ 60Hz (non-HDR). One is UW.

So when I turned off HDR on the 4K, mem clocks dropped to 5001.

Now here is the kicker. I turned HDR back on again and changed the refresh to 144Hz. And bingo, mem clock drops to 405 (without HDR I think this went even lower, so plenty bandwidth).

Tried various other refresh rates but 60 and 59.9 would always get stuck at max speed. 50Hz dropped to 5001. Every else behaves fine.

@:D:D What is that app you are using? Not the GPU-Z one, the one above?

 

[:D:D]

Just something I knocked up to check a few things. Some time ago posted a heaven bench with GPU OC set and read at 12.5MHz which scored a lot higher than expected.
https://www.techpowerup.com/forums/...0-benchmark-scores-part-2.222125/post-5096125
Effective clocks were something like 40x higher if IIRC. So I prefer to see effective clocks plus there's some other bonus stuff, it's compact and works well enough for me from userland both under Windows and Linux, well except for UEFI version number which seems to be missing so far under nvidia linux driver.

 

[Zach_01]

I always had VRR on since the latest display but my GPU was not idling well enough. most of the time was at 45-50W with rarely down to 28-30W.
After enabling dynamic refresh from Win11 settings is idling mostly between 21~27W. Still around ~48W for video/movie but at least doesn't need fans.
The monitor has support of 1MHz but I really doubt its going so low.

 

[Ruru]

Full blast here as well. 4K120 & 4K60 monitors.