1080 SLI power utilization low, 8x/8x PCIe lanes issue?

[pegnose]

Even with SLI turned off and power target set to 120% TDP my 1080 FTW won't draw the power it is allowed to (except in Furmark, where it goes up to 115%) even if it is 98-99% busy as in Fire Strike. In Fire Strike Ultra it is 85-95% TDP.

If SLI is on and employed by game or application, neither card will ever go far beyond 85%. It is even not unusual to see 45-55% power draw with SLI on games like Dishonored 2.

I am rather new to Multi GPU. Is this due to the fact that my ASUS VIII Hero is running in 8x/8x PCIe mode once two cards are installed?

 

[pegnose]

Nope, doesn't seem to be the whole story. Took one card out and no difference in Fire Strike. Fire Strike Ultra sometimes touches the 105 % mark but only in the first part. The second part only utilizes ~80% of the power budget.

EDIT: Anybody else not being able to unleash the full power of your new cards?

 

[pegnose]

Btw, CPU is a 6700k @ 4.6 GHz far from being fully loaded, RAM is 32 GB @ 3000 MHz. So no issues here.

Is this the memory bandwidth bottleneck people are talking about regarding the 1080s? Single card currently is OCed to +70 MHz Core / +400 MHz Memory.

Or are there simply no games or applications yet being able to fully utilize these cards?

 

[pegnose]

The Strix GTX 980ti OC I had before was hitting the 120% power limit easily.

 

[bystander36]

Why does it matter if it hits the power draw limit if it hits the proper clocks and can hit 100%(99%) usage? The power draw is there to give the card enough power to operate at full usage, which it likely is. You don't want it to use more power if it doesn't have a use for it.

 

[pegnose]

That's a good question. I don't perfectly know, it is more of an intuition, but I would say the card is not living up to it's full potential. With every card I had before I could lift the power cap and would get more performance, even if it had been running at 97-99% load before (like with the 980 Ti). So the load is not really telling anything about max performance in my experience. The clocks neither: the GPU turbo needs a proper trigger to be maxed out (if temps allow it; e.g. the EVGA Precision tool can tell the card to run at max for getting immediate OC feedback). But that isn't saying anything about whether the card spends its time useful or not.

EDIT: I think what bugs me most is that Furmark can create a power load that no other application can produce - while with Maxwell max power draw was always more or less identical between torture and gaming.

 

[bystander36]

The 1080 is a very efficient card. It likely just doesn't need all the power given to it in any way. Test its performance, it's clock rate and usage. If something doesn't add up, then worry. Using all the power given to it is not something we desire. That is only important if the card isn't operating at its full potential.

 

[pegnose]

Well, If in-game my card is drawing only 70-80% of its TDP, then I get the strong feeling it doesn't.

 

[bystander36]

Well, If in-game my card is drawing only 70-80% of its TDP, then I get the strong feeling it doesn't.

I have a strong feeling that there is absolutely nothing wrong.

Now test it, and get back to us. Download MSI Afterburner, look at the clocks and usage while in game and tell us what you find. You are most likely going to find one of 2 things, 1) usage and/or clocks are low, as a result of some bottleneck or v-sync, or 2) it works at 100%. Neither are bad in terms of your GPU's.

 

[pegnose]

SLI on: G-Sync on, Fps ~90, 1949 Mhz core, 76 and 65 °C, both ~60% load, both ~45% power, both in SLI Sync limit (for whatever reason in that Fps area on 1080p)
SLI off: G-Sync on, Fps ~70-75, 1936 MHz core, 80 °C, -85-90% load, ~65% power, voltage limit (which means "no other limit", afaik)

CPU ist ~50 %, RAM is 8/32 GB

So why is the darn thing not just doing more?! But ok, maybe that is just buggy Dishonored 2.

 

[pegnose]

And no, I don't mean my GPUs are bad. I mean: why the HECK is it not going the full way?!

Same with the last Deus Ex, btw.

 

[bystander36]

Power consumption is on a need basis. If you have good binned GPU, they do not need the same power of other GPUs. You don't want it to use all the power. One of the more common things OCers do is reduce the voltage of a card so it uses less power. This not only reduces power usage, but reduces the heat the card produces, and reduces noise levels. It can also allow for higher clocking in some cases too.

Test the GPU usage, and clocks, forget about the power consumption until you actually have a problem.

 

[pegnose]

I did test, see above. The card is 10% idle, 90 % load.

 

[bystander36]

I did test, see above. The card is 10% idle, 90 % load.

You are testing power usage, not GPU usage for the most part. I see you added some tests recently.

You have GTX 1080 SLI at 1080p. You are going to be CPU bound in most cases. Even with 1, you will be CPU bound often with a GTX 1080, game dependent. 50% usage on the CPU does not mean you are not CPU bound. Most CPU bound situations are the result of 1 core. And there are memory bound situations too. There is a reason most people consider a GTX 1080 as a 1440p card. GTX 1080 is more power than 1080p needs, GTX 1080 SLI is ridiculously over kill for that resolution.

Turn on VSR in the Nvidia control panel, and go into a game and set it to 4K resolution. Your GTX 1080's will be used fully in most games then. At that point, you will likely they'll use more power, but don't expect 120%. That slider does not make the GPU usage 120% normal power. It "allows" the GPU to use up that much power, but only when it needs it.

 

[pegnose]

50% usage on the CPU does not mean you are not CPU bound. Most CPU bound situations are the result of 1 core. And there are memory bound situations too.

So you are saying that I would see at least 100% load if going to QHD. That is the most reasonable explanation, I am afraid. I'll try that, thank you.

It is only strange that I hit the CPU limit at such low Fps as 90. Also I am wondering why manufacturers denote a TDP that is seldom reached. Usually they like to show low values here.

There is a reason most people consider a GTX 1080 as a 1440p card. GTX 1080 is more power than 1080p needs, GTX 1080 SLI is ridiculously over kill for that resolution.

No it is not. I'd like to play my games at high frame rates. What did I buy a 144 Hz G-Sync display for?! It is people in the media constantly repeating that 40-50 Hz in 1st person games is "perfectly smooth" who break this experience for enthusiast gamers like me - which is ridiculous, btw.

Turn on VSR in the Nvidia control panel, and go into a game and set it to 4K resolution. Your GTX 1080's will be used fully in most games then. At that point, you will likely they'll use more power, but don't expect 120%.

I tried that. Dishonored 2 just stays black on my machine with a virtual 4k resolution. Fire Strike Ultra does use more power then, but not across all tests (didn't check, but assume load also is max then).

That slider does not make the GPU usage 120% normal power. It "allows" the GPU to use up that much power, but only when it needs it.

Yes, that is clear. Only this card behave so differently from what I am used to. Maybe that is most of the story.

 

[pegnose]

Sorry, wrong button. Pls delete.

 

[bystander36]

Buying 1 GTX 1080 for a 1080p 144hz monitor is a reasonable choice. Buying 2 is just going to cause you to bottleneck a ton. I've had a 120hz monitor for about 6 years now. It's great and all, but 120 FPS is not achievable in many if not most games, even at low settings, but that does not mean that 120 hz isn't extremely useful. One obvious benefit is you don't need to use V-sync, because the refresh rate is so fast, tearing is far less noticeable. As a result, 80+ FPS without v-sync is my target in most games. If the game can handle more, great, but don't expect it.

Buying 2 GTX 1080's for 1080p is beyond overkill. There will be next to no games which will use your GPU's fully. If you want to use it, use VSR at 4K, or at least beyond 1440p. You could run into issues with some games which don't support some of those resolutions, but most newer games should work.

 

[pegnose]

I think I get that now, slowly. :/

Still I am hoping that pure PC games will give better performance (and then SLI scaling) than these crappy console ports (Dishonored 2, DXMD). Dying Light was running like hell on my GTX 980 Ti (120-144 Hz depending on settings), I should give it a try with SLI.

The second reason behind going SLI was VR SLI (which isn't actually SLI at all, I know, but uses one card per eye). And if going SLI at all, I wanted to be fine for some years (-> 1080s, and not 1070s). There might be some games demanding more than 8 GB VRAM soon for max details, but other than that those two should last a while.

UNFORTUNATELY, there currently is only one VR 'game' using VR SLI: Everest, a beautiful 'simulation' of making it to the top. But, very recently VR SLI was included in into the Unreal engine and Unity (a beta branch atm). So there is still hope!

 

[bystander36]

I'm not sure it would be any better if games were designed for the PC first. Because they are console ports, they are being designed for more cores than before, and they limit some of what is done so consoles can handle the games. The ugly truth is that developers do not design games around refresh rates higher than 60hz. Those who want 144hz gaming, have to live with the fact that dev's just do not consider that into their decisions, with the exception of Counter Strike games (maybe a handful of others I don't know of).

I have also done SLI for the sake of 3D Vision, and it worked pretty well. Unfortunately, 3D Vision isn't well supported since DX9 died. I am hoping VR will bring back support.

 

[pegnose]

I have the slight feeling that console games being designed for AMD hardware are just not running well on NVidia cards. Also some console material is deliberately limited to 30 Hz, no? Which eliminates the need for code optimization, because the PS4 has all the time in the world for getting things done. And that might exactly be the reason why those games run badly on good hardware: a lot of frame time passes while the hardware is more or less idle.

 

[bystander36]

I wouldn't worry about the AMD designed games. They typically have less overhead for Nvidia cards, allowing for higher top end FPS. It's not an issue of having enough GPU power, when it comes to high FPS, but CPU power. AMD drivers have historically required more CPU power to run their GPU's. Even then, we aren't talking about a lot of difference. The problem is that the CPU must feed the GPU instructions for every frame rendered, and there is a limit to how many frames the CPU can keep up with. It doesn't typically change much with different settings.

The dev's simply do not design a game to run at 144 FPS, and as long as they can hit 60 FPS, they do not see a reason to push for more. Some games will go higher. Not by design, but by accident.

 

[Headfoot]

I think you're just straight up CPU limited. Dishonored 2 is a turd of a port right now on PC so its not a great use case. 2x1080 is a lot of power. I dont know if there are many DX12 games that support 2xSLI that you can try besides DXMD.

If you haven't overclocked your CPU, overclock it and see if your FPS improves. I'm sure it will

 

[bystander36]

He didn't mention the CPU or resolution until later, but he has a 6700k @ 4.6 GHz, and is at 1080p. He most certainly is going to be CPU bound with GTX 1080 SLI.

 

[pegnose]

Ok, this is really amazing, I should have tested some more games (beyond console ports) before posting here:

I have tried Dying Light in 1080p (native res) with all it has to offer (Ultra with PCSS enabled), and I am way above 100 Fps with just one card! Then I looked at SLI scaling, which is immense! First I set DSR to 2x and was at 55-60 Fps with one card. After re-enabling SLI I got ~115 Fps at the same loading point. Holy cow!

Of course, GPU load is at 99% now (how else). And power utilization still is robustly below 100%, so the efficiency hypothesis probably is right.

Anyways, I am just happy that there are indeed games out there with which my newly upgraded rig can show its qualities.

 

[Headfoot]

Yeah Dying Light is now in a really good state, quite well optimized considering the solid visuals