GTX 1080 Ti 'Hybrid' Benchmarks: Removing the Thermal Limit P2: 1080 Ti Hybrid Thermal Analysis P3: 1080 Ti Hybrid Benchmarks (FPS)

We’ve fixed the GTX 1080 Ti Founders Edition ($700) card. As stated in the initial review, the card performed reasonably close to nVidia’s “35% > 1080” metric when at 4K resolutions, but generally fell closer to 25-30% faster at 4K. That’s really not bad – but it could be better, even with the reference PCB. It’s the cooler that’s holding nVidia’s card back, as seems to be the trend given GPU Boost 3.0 + FE cooler designs. A reference card is more versatile for deployment to the SIs and wider channel, but for our audience, we can rebuild it. We have the technology. “Technology,” here, mostly meaning “propylene glycol.”

To improve performance, as discussed on the thermal testing page of that review, increasing the fan RPM to intolerable levels would allow greater boosting potential on the GPU by removing a thermal constraint. The GTX 1080 Ti and its host GP102 GPU impose a hard limiter at 84C, employing a fan curve that favors 50% speeds (better for noise, worse for cooling) and leveraging clock limiting to keep that temperature. Here’s that page, if you missed the thermal and frequency vs. temperature & time testing.

One curiosity we’ve always had with these Hybrid mods has been VRM temperature, though; we’ve long hypothesized that modifying the reference design could negatively impact VRM/FET cooling, given the imposition of a block in front of air flow and removal of the heatsink. In today’s testing, we’re deploying thermocouples to FET2 & FET7 to log temperature under each cooler deployment. We’re looking into VRAM testing in the future.

Even if you’re not planning to go through the few-step process of building your own Hybrid card (atop the foundation of a reference design), this content should still be of interest: By removing the thermal constraint, we’re able to project performance of AIB partner 1080 Ti cards with better cooling. That’s without accounting for any pre-OCs, though Boost 3.0 does a good job of basically pre-overclocking for the lazy end-user.

We’re still working on the 1080 Ti follow-up coverage, including noise (dBA) and overclock testing. For today, we’ve got a more thorough look at clock behavior, FPS under thermally unconstrained scenarios, and some light overclocking. Limitations from nVidia on voltage don’t help us hit higher clocks, but we can still run some more tests than we’ve done for today. All in time. There’s a lot going on in the industry, lately, as we’re already on the way to the next event.

Let’s look at the GTX 1080 Ti FE’s performance when put under liquid, then see how FPS and performance increase with better cooling.

GPU Testing Methodology

For our benchmarks today, we’re using a fully rebuilt GPU test bench for 2017. This is our first full set of GPUs for the year, giving us an opportunity to move to an i7-7700K platform that’s clocked higher than our old GPU test bed. For all the excitement that comes with a new GPU test bench and a clean slate to work with, we also lose some information: Our old GPU tests are completely incomparable to these results due to a new set of numbers, completely new testing methodology, new game settings, and new games being tested with. DOOM, for instance, now has a new test methodology behind it. We’ve moved to Ultra graphics settings with 0xAA and async enabled, also dropping OpenGL entirely in favor of Vulkan + more Dx12 tests.

We’ve also automated a significant portion of our testing at this point, reducing manual workload in favor of greater focus on analytics.

Driver version 378.78 (press-ready drivers for 1080 Ti, provided by nVidia) was used for all nVidia devices. Version 17.3.1 was used for AMD.

Moving forward, we’re refreshing our GPU bench with the relevant high-end contenders: The GTX 1080 Ti, GTX 1080, and GTX 1070 in Founders Edition variants, with a splash from the GTX 980 Ti. We’re also going to add in the RX 480, but note that it competes in a completely different price bracket. That’s just to give some representation for a $250ish card. We’ll add Vega once it’s ready, and will slowly add more GPUs to this bench with each content piece. We do lose the Titan XP in this process, sadly, as our original model was a loaner.

Please note that due to limited time between events, we’re not going to be getting into noise level measurement and deep overclocking today. We’ll look into those post-PAX in some special features.

A separate bench is used for game performance and for thermal performance.

Thermal Test Bench

Our test methodology for the is largely parallel to our EVGA VRM final torture test that we published late last year. We use logging software to monitor the NTCs on EVGA’s ICX card, with our own calibrated thermocouples mounted to power components for non-ICX monitoring. Our thermocouples use an adhesive pad that is 1/100th of an inch thick, and does not interfere in any meaningful way with thermal transfer. The pad is a combination of polyimide and polymethylphenylsiloxane, and the thermocouple is a K-type hooked up to a logging meter. Calibration offsets are applied as necessary, with the exact same thermocouples used in the same spots for each test.

Torture testing used Kombustor's 'Furry Donut' testing, 3DMark, and a few games (to determine auto fan speeds under 'real' usage conditions, used later for noise level testing).

Our tests apply self-adhesive, 1/100th-inch thick (read: laser thin, does not cause "air gaps") K-type thermocouples directly to the rear-side of the PCB and to hotspot MOSFETs numbers 2 and 7 when counting from the bottom of the PCB. The thermocouples used are flat and are self-adhesive (from Omega), as recommended by thermal engineers in the industry -- including Bobby Kinstle of Corsair, whom we previously interviewed.

K-type thermocouples have a known range of approximately 2.2C. We calibrated our thermocouples by providing them an "ice bath," then providing them a boiling water bath. This provided us the information required to understand and adjust results appropriately.

Because we have concerns pertaining to thermal conductivity and impact of the thermocouple pad in its placement area, we selected the pads discussed above for uninterrupted performance of the cooler by the test equipment. Electrical conductivity is also a concern, as you don't want bare wire to cause an electrical short on the PCB. Fortunately, these thermocouples are not electrically conductive along the wire or placement pad, with the wire using a PTFE coating with a 30 AWG (~0.0100"⌀). The thermocouples are 914mm long and connect into our dual logging thermocouple readers, which then take second by second measurements of temperature. We also log ambient, and apply an ambient modifier where necessary to adjust test passes so that they are fair.

The response time of our thermocouples is 0.15s, with an accompanying resolution of 0.1C. The laminates arae fiberglass-reinforced polymer layers, with junction insulation comprised of polyimide and fiberglass. The thermocouples are rated for just under 200C, which is enough for any VRM testing (and if we go over that, something will probably blow, anyway).

To avoid EMI, we mostly guess-and-check placement of the thermocouples. EMI is caused by power plane PCBs and inductors. We were able to avoid electromagnetic interference by routing the thermocouple wiring right, toward the less populated half of the board, and then down. The cables exit the board near the PCI-e slot and avoid crossing inductors. This resulted in no observable/measurable EMI with regard to temperature readings.

We decided to deploy AIDA64 and GPU-Z to measure direct temperatures of the GPU and the CPU (becomes relevant during torture testing, when we dump the CPU radiator's heat straight into the VRM fan). In addition to this, logging of fan speeds, VID, vCore, and other aspects of power management were logged. We then use EVGA's custom Precision build to log the thermistor readings second by second, matched against and validated between our own thermocouples.

The primary test platform is detailed below:

Note also that we swap test benches for the GPU thermal testing, using instead our "red" bench with three case fans -- only one is connected (directed at CPU area) -- and an elevated standoff for the 120mm fat radiator cooler from Asetek (for the CPU) with Gentle Typhoon fan at max RPM. This is elevated out of airflow pathways for the GPU, and is irrelevant to testing -- but we're detailing it for our own notes in the future.

Game Bench

BIOS settings include C-states completely disabled with the CPU locked to 4.5GHz at 1.32 vCore. Memory is at XMP1.

We communicated with both AMD and nVidia about the new titles on the bench, and gave each company the opportunity to ‘vote’ for a title they’d like to see us add. We figure this will help even out some of the game biases that exist. AMD doesn’t make a big showing today, but will soon. We are testing:

Ghost Recon: Wildlands (built-in bench, Very High; recommended by nVidia)

Sniper Elite 4 (High, Async, Dx12; recommended by AMD)

For Honor (Extreme, manual bench as built-in is unrealistically abusive)

Ashes of the Singularity (GPU-focused, High, Dx12)

DOOM (Vulkan, Ultra, 0xAA, Async)

Synthetics:

3DMark FireStrike

3DMark FireStrike Extreme

3DMark FireStrike Ultra

3DMark TimeSpy

For measurement tools, we’re using PresentMon for Dx12/Vulkan titles and FRAPS for Dx11 titles. OnPresent is the preferred output for us, which is then fed through our own script to calculate 1% low and 0.1% low metrics (defined here).

Continue to Page 2 for thermal & clock-rate analysis (and synthetics).