The goal for today is to trick an nVidia GPU into drawing more power than its Boost 3.0 power budget will allow it. The theoretical result is that more power will provide greater clock stability; we won’t necessarily get better overclocks or bigger offsets, but should stabilize and flatline the frequency, which improves performance overall. Typically, Boost clock bounces around based on load and power budget or voltage. We have already eliminated the thermal checkpoint with our Hybrid mod, and must now help eliminate the power budget checkpoint.
This content piece is relatively agnostic toward nVidia devices. Although we are using an nVidia Titan V graphics card, priced at $3000, the same practice of shunt resistor shorting can be applied to a 1080 Ti, 1070, 1070 Ti, or other nVidia GPUs.
“Shunts” are in-line resistors that have a known input voltage, which ultimately comes from the PCIe connectors or PCIe slot. In this case, we care about the in-line shunt resistors for the PCIe cables. The GPU knows the voltage across the shunt (12V, as it’s in-line with the power connectors), and the GPU also knows the resistance from the shunt (5mohm). By measuring the voltage drop across the shunt, the GPU can figure out how much current is being pulled, and then adjust to match power limitations accordingly. The shunt itself is not a limiter or a “dam,” but a measuring stick used to determine how much current is being used to drive the card.
This content piece is video-centric, but we have a full-length feature article coming tomorrow -- and it's focused on shunt shorting, something we have spent the past few days playing around with. For today's, however, we point you toward our render rig's GPU diagnostics, where we pull a Maxwell Titan from the machine, try to determine why it's overheating, and show some CLC / AIO permeation testing in the process. Rather than weigh the loops, which makes no sense (given the different manufacturing tolerances for the radiators and pumps), we emptied two loops -- one new and one old -- to see if the older unit's liquid had permeated the tubes. If it had, then we'd measure less liquid in the older loop, showing that a year of heavy wear had caused the permeation. You can find out what happened in the video below.
The short of it is that, between the two loops, we saw no meaningful permeation -- we also noted that the pump impellers were still spinning, and that the thermal paste seemed fine. Our next steps will be to remount the CLC and test again.
Fortunately, this GTX 1060 isn't prepped for mass market or DIY consumer adoption -- we've got enough confusing naming as is. The GTX 1060 presently exists in 3GB and 6GB AICs, with the former also containing one fewer SM (or a 10% core reduction). There is also the lesser-known 1060 6GB card with boosted 9Gbps memory speeds, part of a refreshed effort by nVidia and its partners earlier this year. According to Chinese language website Expreview, a new GTX 1060 5GB card is allegedly planned for release in Asian markets, primarily targeted for use in internet cafes and PC bangs. We have not independently verified the story at this time.
From what the story indicates, it seems as if this particular GTX 1060 model will carry the original 1280 CUDA cores (as opposed to the 1152 FP32 lanes on the 1060 3GB), with the primary difference existing in a 1GB reduction to capacity and 160-bit memory interface.
This episode of Ask GN, shipping on Christmas day, answers a few pertinent questions from the last few weeks: We'll talk about whether we made ROI on the Titan V, whether it makes more sense to buy Ryzen now or wait for Ryzen+/Ryzen2, and then dive into the "minor" topics for the segment. Smaller topics include discussion on choosing games for benchmarking -- primarily, why we don't like ROTTR -- and our thoughts on warranty/support reviews, with some reinforced information on vertical GPU mounting. The conclusion focuses on an ancient video card and some GN modmat information.
The embedded video below contains the episode. Timestamps are below that.
The monstrosity shown in our latest GN livestream was what ranked us among the top-10 on several 3D Mark world benchmarks: It was a mixture of things, primarily including benefit of having high-end hardware (read: buying your way to the top), but also compensating for limited CPU OC skills with a liquid cooling mod. Our Titan V held high clocks longer than it had any business doing, and that was because of our Titan V Hybrid Mod.
It all comes down to Boost 3.0, as usual, and even AMD’s Vega now behaves similarly. The cards look at their thermal situation, with nVidia targeting 83-84C as a limiter, and then adjust clocks according to thermal headroom. This is also why there’s no hard guarantee on clock speed, because the card functionally “overclocks” (or “downclocks,” depending on perspective) itself to match its thermal budget. If we haven’t exceeded the thermal budget – achievable primarily with AIB partner coolers or with a liquid mod – then we have new budgets to abide to, primarily power and voltage.
We can begin solving for the former with shunt mods, something we’ve done and for which we’ll soon publish data, but we can’t do much more than that. These cards are fairly locked down, including BIOS, and we’re going to be limited to whatever hard mods we can pull off.
We previously went through the process of dismantling, draining, and refilling an Enermax Liqtech TR4 closed-loop liquid cooler (some call these "AIOs") in an attempt to determine how serviceable the CLCs are. This particular cooler wasn't too difficult to refill, as we showed in our accompanying video, but we still wanted to check thermal results to see if the cooler had worsened in performance. The goal wasn't to make it better, just to see if it could be serviced, and without negative impact to cooling ability.
Keep in mind that fluid selection will matter: If the CLC mixes metals, as many do, you'll want to include a biocide of some sort in your refill. There are plenty of mixtures that would achieve this. We used an EK Cryofuel with biocide additive, with distilled water as the primary component (>90%) for the liquid composition. Our thermal test methodology is the same as in all our Threadripper cooler reviews, including the Enermax 360 vs 240 review. If curious how we tested, head over there.
There’s just barely time left for online Christmas shopping, and retailers know it. For once, Amazon’s deals have synchronized with Newegg’s, and there are discounts across the board. We’ve collected some of the best last-minute deals. Remember: if you order it before the 25th, you technically didn’t forget.
The Cougar Conquer is an open-air case with a unique design that’s already attracted a lot of attention. We’ve reported on Cougar products in the past and reviewed their budget 200K keyboard back in 2015, but this is the first hands-on experience we’ve had with one of their enclosures. Cougar gets some points by default for managing to ship a glass-panelled case from Asia without anything shattering, unlike another case we received (review coming soon).
The Conquer is a huge case. It’s easy to underestimate its size in pictures because of its unusual shape, but it’s large enough to easily fit a full ATX board at a diagonal, making it both taller and wider than standard cases. The vast majority of the chassis is constructed from 5mm thick aluminum and both sides are tempered glass, making it much heavier than the skeletal frame implies. It’s technically an open air chassis, but with a case-like frame, providing mounting points for several fans.
We never bothered to review Fractal’s popular Define R5--by the time we got a chance, it was already old news. Since the R5’s release, we’ve reviewed both the Define C (and Meshify C) and given them very high marks. Now, the R5’s successor is here, ready for 2017 with a full PSU shroud and a tempered glass side panel. There are no LEDs, though, so we must all mourn.
OK, mourning over. This Fractal Define R6 review looks at build quality, thermal and acoustic performance, and cable management features. This enclosure is one of the few to impress us in the last few months, given the prevalence of cases like the Bitfenix Enso, and we found the R6’s build quality to be even better than the already-liked Define/Meshify C.
We’ve previously found unexciting differences of <1% gains between x16 vs. x8 PCIe 3.0 arrangements, primarily relying on GTX 1080 Ti GPUs for the testing. There were two things we wanted to overhaul on that test: (1) Increase the count of GPUs to at least two, thereby placing greater strain on the PCIe bus (x16/x16 vs. x8/x8), and (2) use more powerful GPUs.
Fortunately, YouTube channel BitsBeTrippin agreed to loan GamersNexus its Titan V, bringing us up to a total count of two cards. We’ll be able to leverage these for determining bandwidth limitations in supported applications; unfortunately, as expected, most applications (particularly games) do not support 2x Titan Vs. The nature of being a scientific/compute card is that SLI must go away, and instead be replaced with NVLink. We must therefore rely on explicit multi-GPU via DirectX 12. This means that Ashes of the Singularity will support our test, and also left us with a list of games that might support testing: Hitman, Deus Ex: Mankind Divided, Total War: Warhammer, Civilization VI, and Rise of the Tomb Raider. None of these games saw both Titan V cards, though, and so we only really have Ashes to go off of. It goes without saying, but that means this test isn’t representative of the whole, naturally, but will give us a good baseline for analysis. Something like GPUPI may further provide a dual-GPU test application.
We also can’t test NVLink, as we don’t have one of the $600 bridges – but our work can be done without a bridge, thanks to explicit multi-GPU in DirectX 12.
It’s time to revisit PCIe bandwidth testing. We’re looking at the point at which a GPU can exceed the bandwidth limitations of the PCIe Gen3 slot, particularly when in x8 mode. This comparison includes dual Titan V testing in x8 and x16 configurations, pushing the limits of the 1GB/s/lane limits of the PCIe slots.
Testing PCIe x8 vs. x16 lane arrangements can be done a few ways, including: (1) Tape off the physical pins on the PCIe foot of the GPU, thereby forcing x8 m ode; (2) switch motherboard PCIe generation to Gen2 for half the bandwidth, but potentially introduce variables; (3) use a motherboard with slots which are physically wired for x8 or x16.
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