AnandTech: Thermalright Ultra 120: Elegant, Fanless and Efficient Cooling

Fanless Cooling

The Ultra 120 is based on the design of the fanless HR-01, so we were interested in seeing how the Ultra 120 performed without a cooling fan.

FANLESS X6800 Stock (2933MHz) IDLE Temperature

Even without a cooling fan the Ultra 120 managed to keep the CPU cool at idle. This performance is actually a bit better than the stock Intel retail HSF which does have a fan. Where the very good Intel stock cooler keeps the X6800 at 41C at idle, the fanless Ultra 120 can manage an even better 36C, with no fan at all.

Cooling efficiency of the fanless Thermalright Ultra 120 was also compared under load conditions at stock speed by continuously looping a benchmark test of Far Cry. The Far Cry River demo is looped for 30 minutes and the CPU temperature is captured at four second intervals with the NVIDIA monitor "logging" option. The highest temperature during the stress test is then reported. Momentary spikes are ignored, as we report a sustained high-level temp that you would expect to find in this recording configuration.

FANLESS X6800 Stock (2933MHz) LOAD Temperature

The temperature after 8 minutes of heavy load testing reached 47C. During the 30 minutes of testing the Ultra 120 never exceeded 62C. It also quickly returned to 48C after the stress testing, but it took quite a while to return to the idle 36C. This demonstrates that our case setup is very poor for a fanless CPU cooler.

Our stock OCZ PowerStream 520 is a poor design for a fanless cooling system. Thermalright recommends a power supply with a down-facing fan (one that removes air from the CPU area) be used for cooling for the fanless HR-01. Many other power supplies use this design and they would definitely improve fanless performance of the Ultra 120. Therefore our fanless test results should be considered absolute worst case.

Fanless Overclocks

Fanless benchmarks were also run at two moderate overclocks. At 3.2GHz (12x267 at default voltage), temperatures started at 40C. We measured temperatures after each 8 minutes of load test and found maximum temperatures at 58C-67C-71C-82C. The system never failed even though temperatures as high as 82C were reached during testing. It is again clear our case design is not exhausting enough air for this cooler in fanless operation while it is overclocked.

Tests were also run fanless at 3.5GHz (13x277 at stock voltage). Idle at 3.5GHz fanless was 50C. 8-minute interval stress temperatures were 69-75-81-fail. We are confident that a better ventilated case and a power supply with a down facing fan above the CPU would improve air flow enough for day-in and day-out operation at moderate overclocks with a fanless Ultra 120. With no case fans, no CPU fan, and a power supply that exhausts air only to the rear there was nothing to adequately remove heat from the case/CPU. With a reasonable case/PSU setup for fanless use you will likely get performance levels close to our first set of load measurements.

It is clear from the Ultra 120 testing without a fan that this heatsink can easily cool a Core 2 Duo at stock speed without a fan. It also will likely handle moderate overclocks at stock voltages. It is important to use a power supply with a CPU down-facing fan for best fanless performance. Case exhaust fans would also help, as well as rear fan ducts such as those supplied on the Thermalright HR-01 fanless cooler.

For those whose main concern with cooling is low noise the ability to cool with no fan at all is hard to beat. Fanless CPU cooling requires careful attention to airflow in the case and the design of the power supply, but the reward is the lowest noise possible with air cooling.