VGA Coolers: Thermalright V1 Ultra, Zalman 700 & 900, AC Silencer 5 v.3

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TEST 5: Experiments with the VF900CU

Much of the VF900's advantage seemed to come from the fact that the speed of its fan seemed to have very little effect on its cooling efficiency. When the coolers were compared with the fans at full speed, the VF900 was good, but the V1 Ultra was slightly better. However, when the fans were turned down, the VF900 was clearly better because its effectiveness simply didn't change. In contrast, the V1 Ultra ran much hotter under low airflow. Why? Re-testing proved that the initial results were not an anomaly, but how was it possible that the speed of the fan simply had no effect?

To answer this question, we decided to modify the airflow in our test rig. A 92mm fan vent on the side panel — blocked off during ordinary testing — proved to be the modification we were looking for. The vent was located more or less directly above the expansion slots on the motherboard, slightly below the top slot the was occupied by our test card. Unblocking the vent provided a new source of fresh air — and an alternate system airflow which we could use to investigate the VF900 further.

Two tests were run with this side vent unblocked: One with the VGA fan at 12V and one at 5V. The system fan remained at 12V throughout the test so that we could compare the results with our earlier tests.

VF900CU Test Results: Side Vent Comparison
GPU Temperature
VGA Ambient
CPU Temperature
Vent Blocked
VGA Fan @ 12V
Vent Blocked
VGA Fan @ 5V
Vent Unblocked
VGA Fan @ 12V
Vent Unblocked
VGA Fan @ 5V

With the side vent unblocked, the performance was more in line with our expectations. There was a 6°C spread between the fan at 12V and the fan at 5V — not large, but enough to let us know that the VF900 can be affected by fan speed.

What is more interesting is that, while the source of fresh air proved beneficial when the fan was running full tilt, the temperature was actually higher than any other test when the fan speed was reduced to 5V. In addition, the CPU temperature was significantly higher whenever the side vent was unblocked. For a low noise system, the original configuration was clearly a little better.


VGA Cooler Test Results: Fan Noise and MP3 Recordings
Fan Voltage
Arctic Cooling
NV Silencer 5
V1 Ultra

These recordings were made with a high resolution studio quality digital recording system. The microphone was 3" from the edge of the fan frame at a 45¬į angle, facing the intake side of the fan to avoid direct wind noise. The ambient noise during all recordings was 18 dBA or lower.

To set the volume to a realistic level (similar to the original), try playing the Nexus 92 fan reference recording and setting the volume so that it is barely audible. Then don't reset the volume and play the other sound files. Of course, tone controls or other effects should all be turned off or set to neutral. For full details on how to calibrate your sound system to get the most valid listening comparison, please see the yellow text box entitled Listen to the Fans on page four of the article SPCR's Test / Sound Lab: A Short Tour.

By and large, the measured noise levels for the stock fans were all quite similar at a given voltage level. Not surprisingly, the two Zalman fans were very close, with the V1 Ultra being slightly louder and the NV Silencer being slightly quieter across the whole range of voltages. However, these differences were quite minor. All were just a little too loud at full tilt, and all were close to the ambient noise level at 5V.

It was the quality of noise that distinguished the fans from each other, not their volume. In this department, the two Zalman fans were clearly superior, although the VF700 with its clear LED fan was just a tad louder. However, they both sounded quite good when undervolted. MikeC described the noise aptly as "a bit like a whispery rubbing of paper". This is a pleasant change for Zalman, whose past fans have left a lot to be desired with their low voltage noise. This noise character persisted even when the fan voltage was increased; neither fan developed much whine until above 9V.

Compared to the Zalmans, neither the NV Silencer nor the V1 Ultra sounded very nice, although the Revision 3 NV Silencer was considerably improved over the original version. Between the two, the NV Silencer was nicer, but only because it was quieter. Both had a pure tone that could be heard even at 5V. The whine on the V1 Ultra was especially obnoxious because it was so easy to pick out the specific pitch of the noise. The NV Silencer had a different problem: It produced a distinct "chugging" that was noticeable because of its rhythmic quality. Only when the fan was at 12V did the chugging dissipate into a noisy clatter.


At the end of our roundup, Zalman has the advantage with their simple designs, low noise, and excellent performance. The VF900CU in particular had a very strong showing. It was quieter than any other heatsink with the possible exception of the its brother, the VF700CU. And, when the fans were undervolted, it also performed better than any other heatsink by a wide margin. At US$40, it was one of the pricier heatsinks that we tested, but it's still significantly cheaper than many high performance CPU heatsinks.

It's also cheaper than the Thermalright V1 Ultra which, although it did better than any other heatsink with the fan at full speed, did very poorly when undervolted. Its unusual back-mounted fan also raised questions about how well the secondary components on the card were cooled, as the "ambient" temperature reported by our test card was often much higher than the other heatsinks. The large size and complex installation are also disadvantages when compared against Zalman's offerings.

The Arctic Cooling NV Silencer 5 was thrown into the mix as more of a reference than a serious contender — we've reviewed it before. It is costs the least of our contenders, and, although its new fan sounds much better than the old one, it is still comparatively lousy. The fact that a number of existing cards already ship with some version of the NV Silencer installed means that buying it separately is probably not the best way of getting one. The NV Silencer is beginning to look a little dated; we look forward to examining their new Accelero line of VGA coolers sometime in the future.

Last but not least, the VF700CU LED is a good pick for a low or midrange card that doesn't need the extra oomph of the VF900CU. It can be found for as little as US$25 online, and boasts a similar noise character to its bigger brother. It also shares another important characteristic: It seemed to be affected very little by the speed of the fan, which means that it can be undervolted very easily.

As it stands, both of the Zalman heatsinks are viable replacements for a noisy stock cooler. While the market for quiet CPU heatsinks has become quite crowded of late, where VGA heatsinks are concerned, Zalman stands where it did a few years ago with its CNPS7000 series of coolers: There are other competitors on the market, but none is quite as quiet or quite as cool as Zalman's.

Many thanks to Arctic Cooling for the sample of the NV Silencer 5 (rev. 3)
to Zalman for the samples of the VF900CU and the VF700CU LED,
to Thermalright for the sample of the V1 Ultra,
to AOpen for the samples of the VGA card and the motherboard in the testbed,
and to Newegg for the Intel 520 processor.


SPCR Articles of Related Interest:
Fanless PCIe Graphics Cards from Asus and Aopen
Gigabyte GV-N66256DP Fanless AGP video card
Chaintech AA6800GT + Arctic Cooling NV Silencer 5
Arctic Cooling ATI Silencer 2 VGA Cooler
Arctic Cooling VGA Silencer
Zalman ZM-80 VGA Heatpipe Cooler

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