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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
VGA Fan @ 12V
VGA Fan @ 5V
VGA Fan @ 12V
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.
FAN NOISE RECORDINGS
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
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,
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
+ Arctic Cooling NV Silencer 5
Arctic Cooling ATI Silencer
2 VGA Cooler
Arctic Cooling VGA Silencer
Zalman ZM-80 VGA Heatpipe
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