AMD Vega Hybrid Mod: Fixing Power Leakage for Higher OC

By Published July 13, 2017 at 5:12 pm
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Liquid-cooling the AMD Vega: Frontier Edition card has proven an educational experience for us, yielding new information about power leakage and solidifying beliefs of a power wall. We also learned that overclocking without thermal barriers (or thermal-induced power barriers) grants significant performance uplift in some scenarios, including gaming and production, though is done at the cost of ~33A from the PSU over 12V PSU power.

Our results for the AMD Vega: Frontier Edition liquid-cooling hybrid mod are in, and this review covers the overclocking scalability, power limits, thermal change, and more.

The Hybrid mod was detailed in build log form over in part 1 of the endeavor. This mod wasn’t as straight-forward as most, seeing as we didn’t have any 64x64mm brackets for securing the liquid cooler to the card. Drilling through an Intel mounting plate for an Asetek cooler, we were ultimately able to get an Asetek 570LC onto the card, which we later equipped with a Gentle Typhoon 120mm fan. VRM FET cooling was handled by aluminum finstacks secured by thermal adhesive, cooled with 1-2x Corsair ML120 fans. That said, this VRM cooling solution also wasn’t necessary – we could have operated with just the fans, and did at one point operate with just the heatsinks (and indirect airflow).

 

A Reminder on Scope & Focus

Keep in mind that this is largely about thermal and acoustics, not just raw performance. The hybrid mods don’t necessarily provide a whole lot of raw performance headroom, but they do operate significantly quieter and cooler. Although we ultimately achieved additional OC headroom, the actual performance gain (from the previous overclock max) isn’t represented purely in FPS or points. It’s represented best in noise levels, where we see reductions from ~65-70dBA down to ~43dBA, and manage to achieve this reduction in noise alongside a significant, performance-impacting reduction in thermals. We’ll talk about how the thermal headroom improvement benefits clocks on the next page.

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 382.53 was used for all nVidia devices. AMD Vega drivers version 17.6 were used for Vega. Version 17.10.1030-B8 was used for AMD RX series cards.

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.

evga-thermocouples-icx

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 thermal test platform is detailed below:

GN Thermal Bench 2015 Name Courtesy Of Cost
Video Card This is what we're testing - -
CPU Intel i7-5930K CPU 3.8GHz iBUYPOWER   
$580
Memory Corsair Dominator 32GB 3200MHz Corsair $210
Motherboard EVGA X99 Classified GamersNexus $365
Power Supply NZXT 1200W HALE90 V2 NZXT $300
SSD OCZ ARC100
Crucial 1TB
Kingston Tech. $130
Case Top Deck Tech Station GamersNexus $250
CPU Cooler Asetek 570LC Asetek -

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 

GN Test Bench 2017 Name Courtesy Of Cost
Video Card This is what we're testing - -
CPU Intel i7-7700K 4.5GHz locked GamersNexus $330
Memory GSkill Trident Z 3200MHz C14 Gskill -
Motherboard Gigabyte Aorus Gaming 7 Z270X Gigabyte $240
Power Supply NZXT 1200W HALE90 V2 NZXT $300
SSD Plextor M7V
Crucial 1TB
GamersNexus -
Case Top Deck Tech Station GamersNexus $250
CPU Cooler Asetek 570LC Asetek -

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).

Power testing is taken at the wall. One case fan is connected, both SSDs, and the system is otherwise left in the "Game Bench" configuration.

For production testing, we are using an i9-7900X & ASUS X299 Prime Deluxe motherboard with 4x8GB GSkill Trident Z Black memory at 3600MHz with an Enermax Platimax 1350W PSU.

Continue to the next page for Vega overclocking & power leakage.


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Last modified on July 13, 2017 at 5:12 pm
Steve Burke

Steve started GamersNexus back when it was just a cool name, and now it's grown into an expansive website with an overwhelming amount of features. He recalls his first difficult decision with GN's direction: "I didn't know whether or not I wanted 'Gamers' to have a possessive apostrophe -- I mean, grammatically it should, but I didn't like it in the name. It was ugly. I also had people who were typing apostrophes into the address bar - sigh. It made sense to just leave it as 'Gamers.'"

First world problems, Steve. First world problems.

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