Results and Conclusion

To test the HEX 2.0 cooler I decided to use my small form-factor setup, considering the intended use of a compact 95 mm cooler. In larger systems it will be far more cost-effective (and likely better performing) to use a larger all-in-one liquid cooler, but not every case will support even a 120 mm solution. My current mini-ITX setup is no slouch, with an Intel Core i5-6600K processor on an EVGA Z170 motherboard with solid overclocking support, and that last part is important as this Core i5 doesn't present much of a thermal challenge at stock speeds.

I tested the HEX 2.0 along with a couple of other options on hand, with both stock and overclocked CPU loads. For a comparison with a standard air solution of the same size I chose the Noctua NH-U9S, which occupies the same 95 mm footprint and also uses a 92 mm fan. My trusty Corsair H75 120 mm liquid cooler is also included for reference, but, again, the HEX is more intended for situations where even a 120 mm liquid option is not possible, or liquid is simply not desired.

Test Platform
Processor Intel Core i5-6600K
Motherboard EVGA Z170 Stinger (mITX Intel Z170)
Memory Crucial Ballistix Sport 8 GB 2400 MHz DDR4
Graphics Card XFX AMD Radeon 5450 (Fanless)
Storage OCZ Vertex 460 120GB SSD
Power Supply Corsair TX 650W PSU
OS Windows 8.1 64-bit

Temperatures and Noise Levels

Stock results are a little surprising, as the Noctua cooler is more effective with these loads. But the i5-6600k behaves much more like a 65W part than a 91W part at stock workloads (indeed, the non-K Core i5-6600 variant is a 65W part), so to truly test the capabilities of the HEX 2.0 I needed to overclock the CPU. My goal with OC stability is always Prime95, as I use this benchmark to stress the CPU in all of my cooler testing, and I use the highest power draw torture test available in Prime95. I ended up with a rock solid 4.7 GHz overclock from my i5-6600K, but to speed the process up I set a target voltage of 1.34v. All cores were stable at 4.70 GHz throughout all testing, but the voltage was automatically adjusted to a whopping 1.4v (1.399v, to be precise) by my EVGA Z170 Stinger board during those punishing Prime95 runs.

The performance of the HEX 2.0 in this more extreme example is decidedly more impressive, as we see it leapfrog the Noctua cooler to finish behind the Corsair H75 liquid solution. I didn't expect the Hex 2.0 to be able to beat the Corsair H75, but I was pleasantly surprised by how well it fared compared to the dual-fan 120 mm liquid cooler with the overclocked CPU.

As to noise levels, the HEX 2.0 performed better than I was expecting for a design using just a single 92 mm fan, with my SPL meter registering idle noise of just 32.2 dBA (fan speed ~1160 RPM), with load noise of 34.3 dBA (fan at ~1690 RPM), and a high of 40.9 dBA (~2300 RPM) under stress. (All SPL measurements made with a 31.3 dBA noise floor.)

I also measured power consumption from the wall during testing, and the HEX 2.0 certainly will add to your total system power requirements when it is dealing with an aggressive thermal load using the 'insane' preset. I observed power levels of ~39W idle and ~97W load with the 'standard' setting, which is about what this i5-6600K system without a powerful GPU will generally produce under load, but 'insane' mode (which had an identical ~39W idle) produced a high of 138W. Those extra ~40W were not constant, as the software controls the TEC function, using it only as needed to control temps.


We have seen TEC/Peltier products in the past, and even reviewed them in years gone by; but implementing this kind of cooling technology in a consumer CPU cooler has obviously not resulted in a shift in the cooler market to this point. Closed-loop liquid CPU coolers have become commonplace, standard air cooling is better (and increasingly less noisy) than ever, and in general the need for TEC coolers just has not been felt for consumer CPU cooling. I think what Phononic has done with the HEX 2.0 is show the advantage of a TEC in a demanding small form-factor implementation, where liquid coolers will not always fit. A great example of this is a case I have in for review currently: the Lian Li PC-Q17. The only way to install a liquid solution like the Corsair H75 (which I used as a liquid cooler comparison in benchmarks) in the PC-Q17 is to mount it outside of the enclosure, just as with the In Win 901 mini-ITX enclosure I reviewed (way back in 2014). In enclosures like these a small solution is required for a streamlined build, and the HEX 2.0 is a great liquid alternative here.

The HEX 2.0 is overkill for a stock Intel CPU, and didn't fare better than the less expensive Noctua NH-U9S in those tests. Where the HEX 2.0 really showed its potential was in overclocked testing, as I was feeding my Core i5-6600K 1.34+ volts to get Prime95 stable on all cores. The results were far above the Noctua cooler with the voltage that high, showing just how much overhead one has if using the cooler in its most aggressive setting (appropriately called "Insane" mode).  I would love to re-test the HEX 2.0 with an overclocked AMD Ryzen CPU to see just how far a little 95 mm cooler can take a processor like the R7 1700, but that will have to wait. For now I hope the 4.70 GHz OC from my i5-6600K is sufficient to provide an idea of the thermal management this HEX 2.0 is capable of.


  • Premium build quality
  • Very high performance for its size
  • Low noise output from the 92 mm fan
  • Easy to use software


  • Cost
  • Usefulness depends on specific usage scenarios

For the best thermal performance I have seen from a cooler of its size, the Phononic HEX 2.0 is a great option for builds where a liquid cooling loop can't be managed, but aggressive CPU performance (and additional overclocking headroom) is desired. It is expensive, but you are buying a unique product for a specific purpose. If it fits your particular needs, I can think of no better option for demanding thermal loads in this specific form factor.

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