As we mentioned in AMD Ryzen 5 2400G Review: Zen, Meet Vega and AMD Raven Ridge Thermal/Power Analysis: Ryzen CPUs With Vega, the company is using thermal paste instead of solder between its newest dies and heat spreaders. Measurements in the latter story showed that neither Raven Ridge-based model hit its thermal limit using AMD's boxed cooler, even under Prime95. It was only when we pushed the execution cores and graphics engine at the same time that we overwhelmed its stock heat sink and fan.
Of course, this doesn't stop enthusiasts from asking what might have been if AMD had used solder instead, or from speculating about the quality of its thermal paste. And the only way we're going to get answers to either of those questions is removing a Ryzen processor's heat spreader and running some experiments.
A Clean Cut: Heat Spreader Removal
Whether you use a de-lidding tool or a good old fashioned razor blade is up to you. But because AMD employs a silicone-like adhesive layer ~0.2mm thick, the razor blade is a reasonably-priced option. Begin your cut exactly where AMD left a gap in its adhesive.
The only real challenge is getting around the surface-mount components placed close to the adhesive layer. Try positioning the processor vertically and cutting from top to bottom, leading the blade at a slightly slanted angle. Use multiple movements, starting from the outside and cutting in. If you feel resistance, stop immediately, then pull the blade slightly upwards and out.
Next, the old thermal paste needs to be removed from the opened processor. We recommend using a thin, dry fleece cloth, rather than a fuzzy kitchen or paper towel. It is best to wipe around the die in a circle, starting from the outside and moving inwards. You may use a bit of isopropyl alcohol or, if necessary, methylated spirits for cleaning up. However, acetone-based solutions are taboo.
Use the blade (a new one, preferably) to remove any remnants of the silicone glue. This is necessary to ensure that the heat spreader has an even surface to mate with once it's reinstalled, and to avoid too large of a gap.
Intermediate Step: Conventional Thermal Paste
If you go to the trouble of removing the heat spreader, it's highly unlikely that you'd simply swap one thermal paste for another. But rather than going straight to liquid metal, we want to know how AMD's proprietary solution compares to off-the-shelf Thermal Grizzly Kryonaut (one of the best non-conductive, silicone-based thermal pastes available).
So, we're adding one extra step, if only to satisfy our curiosity about AMD's thermal paste and hopefully gain a little more knowledge.
Applying Liquid Metal Paste
For the third and final set of data, we used Thermal Grizzly Conductonaut. This liquid metal "paste" is relatively easy to apply, so long as the die and heat spreader surfaces are absolutely free of grease and dust. Otherwise, the paste won't hold, yielding an unsatisfactory result.
In addition, you need a good, acetone-free clear coat. Try a transparent nail polish without any color or effect pigments. Make sure to shake it well prior to application. To avoid breaking the processor's delicate pins, it helps to rest the chip on a suitable foam surface.
Judiciously cover the surface-mount components and the empty emplacements with your application of polish. Multiple applications may loosen or remove the package's original lacquering, and should thus be avoided. After that, the polish has to be left alone so that it can cure. For the polish to dry properly, wait at least one hour in a warm-enough environment.
Next, it's time to apply the Conductonaut. For this, we cover the die and matching elevation in the heat spreader with a very thin layer. It is better to use a little less at first, and then add more later if needed. The bundled applicator (the thin, attachable top) has to be used. Otherwise, too much of the liquid comes out.
The liquid is then spread in a circular motion using the included foam sticks. Make sure the desired surfaces are covered completely in a thin layer, and that none of the liquid spills over the edge. Should this happen when you go to press the pieces together, the polish you applied will help protect against potential short-circuits.
Finally, the heat spreader is reattached and glued in place with either cyanoacrylate or silicone. All-purpose glue isn't sufficient for keeping the head spreader in place, even if its packaging claims the contents are suitable for metal. Keep in mind that the glue must fill a gap of ~0.2mm so the adhesive still safely connects both sides after curing. Glue would be applied to both sides of the heat spreader, while silicone is only applied to the package. Make sure to attach the heat spreader in its correct orientation.
For perfect pressing and drying, carefully put the processor back into the socket, apply a small dot of high-quality thermal paste, and assemble the boxed cooler carefully. Alternately tighten the screws crosswise, and make sure not to tilt or move the heat sink. After a short temperature check with monitoring software like HWiNFO64, being a burn-in process with Prime95 and be ready to keep an eye on its progress. An hour should be more than sufficient to achieve production-ready performance, though silicone needs about a day to cure properly.
In order to establish the limits of AMD's Raven Ridge-based processors, we need to push them as far as they can go. That's where Alphacool's powerful Eiszeit 2000 Chiller comes into play. We combine it with the Alphacool Eisblock XPX, replacing AMD's Wraith Stealth heat sink. Motherboard components are cooled by 22°C air from a large fan blowing across them.
A short summary of our hardware in table form gives you a quick overview of how we test:
|Test System & Measurement|
|Cooling||AMD Boxed Cooler|
|Case||Microcool Banchetto 101|
|Power Intake||Motherboard Sensors, HWiNFO64, AIDA64, Custom Software|
Contact-free DC measurement at 8-pin EPS connector
Direct voltage measurement at the respective connectors and the power supply
1x Rohde & Schwarz HMO 3054, 500 MHz multi-channel oscilloscope with memory function
2x Rohde & Schwarz HZO50, clamp-on ammeter adapter (1mA through 30A, 100 kHz, DC)
2x Rohde & Schwarz HZ355, test probe (10:1, 500 MHz)
|Operating System||(1709, alle Updates)|
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