ASUS Radeon HD 7870 DirectCU II

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TEST RESULTS

Baseline Power with Integrated Graphics:

Power Consumption Measurements:
GPU Test System (Intel HD 2000 IGP)
State
Idle
CPU Load
CPU + GPU Load
Sys. Power (AC)
36W
74W
87W
Sys. Power (DC)
unknown
61W
72W
System fan speeds: Low
Ambient noise level: 10~11 dBA
System noise level: 12~13 dBA

System with Discrete Graphics:

System Measurements: GPU Test System
(ASUS HD 7870 DirectCU II)
State
Idle
CPU Load
CPU + GPU Load
Temp
CPU
21°C
38°C
56°C
PCH
34°C
41°C
51°C
GPU
31°C
33°C
91°C
GPU VRM
43°C
45°C
93°C
GPU Fan Speed
1080 RPM
3240 RPM
SPL @1m
14 dBA
30~31 dBA
Sys. Power (AC)
50W
90W
264W
Sys. Power (DC)
unknown
75W
250W
Ambient noise level: 10~11 dBA
System noise level on integrated graphics: 12~13 dBA
Ambient temperature: 22°C

With our test system fans on our low speed, 12~13 dBA@1m setting, the HD 7870 DirectCU II ran fairly cool and quiet when idle. The fans were spinning at 1080 RPM but they barely made a dent in the overall SPL and the power draw was only 50W AC which is excellent for a high-end GPU. Putting the system on CPU load had only a 2°C impact on the GPU temperature. The addition of a GPU load pushed the fans to 3240 RPM for a total noise level of 30~31 dBA@1m. The fan control wasn't being overly aggressive though as this measurement was taken after the GPU core had stabilized at 91°C. It was loud, but needed to be to keep the card adequately cooled.

If you only care about idle noise, the HD 7870 DirectCU II is a great choice. Compared to the GPU test system without discrete graphics, the noise level was only 1~2 dB higher, with most of the extra output limited to the 200~500 Hz range. Subjectively, the overall sound was indistinguishable.

On load, the cooler was much louder of course but it also took on a more complex and undesirable acoustic character. The fans became quite whiny and there was also a clearly audible low frequency hum which explains the incredibly sharp tonal peak we observed at ~220 Hz. It doesn't sound great but we've definitely encountered worse.

Noise & Cooling Comparison

Comparison: GPU Test System (Load)
Model
Est. Power Draw (DC)
GPU Temp
SPL @1m
HIS HD 5870 Turbo
GELID Icy Vision @5V
236W
89°C
17~18 dBA
AMD HD 6870 +
GELID Icy Vision @5V
182W
80°C
17~18 dBA
ASUS GTX 680
DirectCU II OC
203W
75°C
27~28 dBA
ASUS HD 7870
DirectCU II
189W
91°C
30~31 dBA
Gainward GTX 560
Ti Phantom
233W
88°C
37 dBA
System fans on low (12~13 dBA@1m).
Ambient temperature: 22°C

You would expect a dual fan cooler to produce good results but the 7870 is quite power hungry and the DirectCU II heatsink is equipped with rather thin fans. The end result is a rather high GPU temperature and noise level compared to what you'd get with an aftermarket cooler. The GELID Icy Vision paired with a HD 5870, which has a much higher power draw, managed to keep the GPU temperature under 90°C while generating an overall system SPL of only 17~18 dBA@1m.

The ASUS GTX 680 DirectCU II OC has a similar looking heatsink to the HD 7870, but it' much larger, with more heatpipes and full-sized fans, and it too, was quieter and cooler despite using more power. That being said, the GTX 680 is about double the price of the HD 7870 so it perhaps is more deserving of a beefed up cooling solution.



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