GN's Thermal Testing Put to the Test in a Thermal Chamber – Validating Our Methods

By Published February 19, 2016 at 5:15 pm
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Thermal testing for cases, coolers, CPUs, and GPUs requires very careful attention to methodology and test execution. Without proper controls for ambient or other variables within a lab/room environment, it's exceedingly easy for tests to vary to a degree that effectively invalidates the results. Cases and coolers are often fighting over one degree (Celsius) or less of separation, so having strict tolerances for ambient and active measurements of diodes and air at intake/exhaust helps ensure accurate data.

We recently put our methodology to the test by borrowing time on a local thermal chamber – a controlled environment – and checking our delta measurements against it. GN's thermal testing is conducted in a lab on an open-loop HVAC system; we measure ambient constantly (second-to-second) with thermocouples, then subtract those readings from diode readings to create a delta value. For the thermal chamber, we performed identical methodology within a more tightly controlled environment. The goal was to determine if the delta value (within the chamber) paralleled the delta value achieved in our own (open air) labs, within reasonable margin of error; if so, we'd know our testing is fully accurate and properly accounts for ambient and other variables.

The chamber used has climate control functions that include temperature settings. We set the chamber to match our normal lab temps (20C), then checked carefully for where the intake and exhaust are setup within the chamber. This particular unit has slow, steady intake from the top that helps circulate air by pushing it down to an exhaust vent at the bottom. It'd just turn into an oven, otherwise, as the system's rising temps would increase ambient. This still happens to some degree, but a control module on the thermal chamber helps adjust and regulate the 20C target as the internal temperature demands. It's the control module which is the most expensive, too; our chaperone told us that the units cost upwards of $10,000 – and that's for a 'budget-friendly' approach.

 

 

Just a Few Concerns & Variables to Account For

Below is a short list of just a few variables or environment settings that must be accounted for:

  • Open loop HVAC changes heavily impact temperatures

  • AC/heat toggling – automatic or manual switching off/on of heating or air will impact results without active ambient logging and delta values

  • Is the case exhaust facing a wall? How far is it from the wall?

  • Surface atop which the case rests could be conforming to the underside (carpet or similar), which would impact thermals

  • Windows in the house or lab will impact results if the case is in direct sunlight.

  • If the wall of the room is an external wall, exposure to heat or cold air (or prolonged sunlight) will gradually increase thermals on that side of the room.

  • Position of air vents (floor/ceiling) will impact thermals if close enough to the case.

  • Heatsink must remain untouched (do not remove/reinstall) to prevent potential for technician error when re-applying thermal compound.

  • Fan speeds must be constant and known.

  • Compound aging and burn-in.

And plenty more.

thermal-chamber-test-2

(Above: Cables shoot through a hole that's drilled in the chamber, usually used to mount thermographic imaging equipment that nears $100,000 in cost; we used this to route cables, then plugged the whole with foam that tested to leak an inconsequential amount of air)

thermal-chamber-test-3

thermal-chamber-test-4

(Above: Additional K-Type thermocouples from the ceiling, routed through the case for various read points)

We've encountered these over the years and have developed what we feel is a solid, reliable case / cooler testing methodology. You can see that in some of our recent reviews, like the Corsair 400C or NZXT Manta reviews.

Most of this is answered by using a dedicated platform for thermals (our case test uses a different bench than our cooler test, which is different than our GPU thermals bench). We use active ambient logging with a thermocouple reader to resolve the rest, then dump all that data into a spreadsheet and compute the deltas.

“Doing it wrong” would be to just check a thermostat's temperature reading and subtract that from the results, since the thermostat likely (1) places its diode in a different location from the test setting, (2) isn't that accurate and may not offer multiple significant figures, and (3) could change. As an example, we've got a thermostat in the hallway connecting our video set and our lab. The thermostat presently reads 70F in the hallway (which is noticeably cooler than Lab A), the production room (Lab B) is reading (with a thermocouple) at 68F, and Lab A is reading at 84F. Massive variance, mostly caused by the accumulation of heat in a room where multiple systems might be running tests. A thermostat is no good.

We run a thermocouple reader near the case. For our thermal chamber testing, we used five total thermocouples to collect as much data as possible: One at rear exhaust (whether or not a fan was present), one 3 inches in front of the front intake, one placed away from intake or exhaust (uninfluenced ambient), one between the intake and CPU cooler fans (internal), and one that moved depending on current test processes.

Much of this data-heavy approach is still being processed, but we're prepared to share early results of our CPU load testing.

The below results show the thermal chamber vs. our lab for CPU load temperatures. We used a SilverStone Kublai KL05 enclosure for this, which is a fairly standard ATX mid-tower.

  Component Courtesy Of Price
Video Card GTX 980 Reference NVIDIA
$500
CPU Intel i5-3570K @ Stock GamersNexus -
Cooler Thermaltake Frio Advance
(1 fan removed)
GamersNexus -
Motherboard MSI Z77-GD65 GamersNexus -
Memory HyperX 2x4GB 1866MHz Fury Kingston $45
SSD HyperX Predator PCI-e 480GB Kingston $400
PSU Enermax Platimax 1350W Enermax $200
Case This is what we're testing! - -

cpu-load-chamber-test

cpu-over-time-load-chamber-test

There's about 0.07C difference between the stock configurations (lab vs. chamber), 0.046C between the bottom intake tests (lab vs. chamber), and 0.225C difference between the tests with an exhaust fan installed. We're postulating that the rear exhaust fan was slightly further apart (but still close) because of the way the exhaust hit the wall of the thermal chamber, then cycled back into rear exhaust vents. The rear fan was only about 3” from the wall. Still, all three results are close and promising news for our lab methodology with case testing.

We'll be performing more of these validation efforts in the near future and will continue to crunch numbers from this initial run. GPU thermals and idle thermals still need to be compiled.

I figured it'd be fun to give a preview to what's going on behind-the-scenes lately, for our regular readers! Remember to check out our Patreon page to help produce more quality content.

Editorial, Test Lead: Steve “Lelldorianx” Burke
Test Technician: Mike "Budekai" Gaglione
B-Roll & Video Editing: Andrew Coleman, Keegan Gallick

Last modified on February 19, 2016 at 5:15 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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