Quick A/B Test: Impact of TR4 Coldplate Size with Noctua NH-U14S

By Published August 22, 2017 at 7:48 pm
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Before Vega buried Threadripper, we noted interest in conducting a simple A/B comparison between Noctua’s new TR4-sized coldplate (the full-coverage plate) and their older LGA115X-sized coldplate. Clearly, the LGA115X cooler isn’t meant to be used with Threadripper – but it offered a unique opportunity, as the two units are largely the same aside from coldplate coverage. This grants an easy means to run an A/B comparison; although we can’t draw conclusions to all coldplates and coolers, we can at least see what Noctua’s efforts did for them on the Threadripper front.

Noctua’s NH-U14S cooler possesses the same heatpipe count and arrangement, the same (or remarkably similar) fin stack, and the same fan – though we controlled for that by using the same fan for each unit. The only difference is the coldplate, as far as we can tell, and so we’re able to more easily measure performance deltas resultant primarily from the coldplate coverage change. Noctua’s LGA115X version, clearly not for TR4, wouldn’t cover the entire die area of even one module under the HIS. The smaller plate maximally covers about 30% of the die area, just eyeballing it, and doesn’t make direct contact to the rest. This is less coverage than the Asetek CLCs, which at least make contact with the entire TR4 die area, if not the entire IHS. Noctua modified their unit to equip a full-coverage plate as a response, including the unique mounting hardware that TR4 needs.

The LGA115X NH-U14S doesn’t natively mount to Threadripper motherboards. We modded the NH-U14S TR4 cooler’s mounting hardware with a couple of holes, aligning those with the LGA115X holes, then routed screws and nuts through those. A rubber bumper was placed between the mounting hardware and the base of the cooler, used to help ensure even and adequate mounting pressure. We show a short clip of the modding process in our above video.

Testing

Testing was fairly straight-forward in this one – we’re not reviewing the cooler today, just looking at coldplate A/B performance.

As above, we fixed the CPU multiplier and voltage to eliminate fluctuations and native boosting behavior during testing. Although the fluctuations and boosting are beneficial to performance, they are unpredictable and invalidate thermal testing. We also used the same 140mm fan (NH-U14S TR4) on each of the coolers; although each unit does include its own fan, there is variance in manufacturing with fan PWM-to-RPM response.

We used three primary tools for CPU load, ultimately eliminating one of them:

  • Prime95 28.5 LFFT (eliminated: The LGA115X cooler couldn’t handle the thermal load, and throttled to a point where differences became immeasurable)
  • Blender 8K render until steady state is achieved and maintained
  • Handbrake 4K transcode until steady state is achieved and maintained

We take measurements at steady state under each workload. Ambient is measured second-to-second during each test, aligned with thermal data from the cooler passes, and then used to offset the output as necessary.

Threadripper’s 1950X throttles at 68C Tdie, or 95C TCTL. We want to be below that value.

Results 

noctua tr4 handbrake 

With Handbrake transcoding one of our videos for 30 minutes, the CPU reaches steady state and produces a temperature delta of 11C between the two. The TR4 coldplate is heavily advantaged in this particular test, keeping to around 57C, versus the nearly throttling LGA115X cooler. Threadripper throttles at 68C Tdie, or 95C TCTL. The idle delta is 3.8C, favoring the TR4 coldplate.

noctua tr4 blender

Moving on to Blender, our load delta is about 10.5C, once again producing a favorable result for the TR4 cooler. There might be a bigger temperature difference than we can see here, as we’re starting to clock throttle on the LGA115X unit.

Liquid will be different, but interesting, because channel design could impact efficiency of the solution. That said, once you’re under liquid, it doesn’t really matter all that much how efficient it is – TR just doesn’t easily get hot enough under existing Asetek CLCs.

Speaking with Noctua about the results after testing concluded, the company reported also seeing about a 10C difference. We’re seeing about what Noctua indicated.

This testing clearly shows that Noctua’s move to update an existing cooler to TR4 IHS sizes, even if the rest of the unit remained unchanged. Noctua likely didn’t have enough lead time to design a completely new cooler, so picked the middle-ground by modifying the coldplate and keeping the rest. The cooler could likely be improved by extending the heatpipes outward to fully contact the perimeter of the coldplate, but in its present state, the heatpipes still contact most (if not all) of the die area.

But again, this isn’t a full review. Interesting results, nonetheless.

Editorial: Steve Burke
Video: Andrew Coleman

Last modified on August 22, 2017 at 7:48 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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