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COOLING THE VIDEO AND TV CARDS
At 95W, the overclocked 7900GT video card is almost as
power-hungry
as the overclocked CPU. The eVGA stock cooler works remarkably well for
a single-slot
design, but has two serious issues: it dumps its heat back into the
case
(and recirculates some of it), and it is unbearably loud when
running 3D loads.
The TV card consumes "only" 25W, but as supplied has no heat
sinks at all, and runs extremely hot in a case with low air flow.
My overall plan was to cool these two cards and the
south bridge separately from the CPU, north bridge and VRM by dividing
the upper chamber of the P180 into two subchambers,
resembling the way the power supply and hard disks are segregated from
the rest of the system. With appropriate baffling and/or ducting,
a fan could supply fresh air to this new chamber, and the hot air could
be exhausted directly out the back of the case.
During the last year, some new video card coolers have come
out that are
as manly as the Ninja. In particular, Aerocase launched its Raven and Condor heat sinks,
gigantic affairs targeted at cooling the toastiest GPUs passively. The
Condor can be ordered in a "reverse wing" orientation, like the sample SPCR reviewed, so that its
radiator sits below the video card far enough away from the motherboard
to allow standard PCI cards to be installed under its wing. This fit my
plan perfectly.
My first task in building the video chamber was to add some
radiators to the TV card. I had
a bunch of Swiftech
MC14 copper RAMsinks
available, and started out by putting them on the very hot parts of the
card: the ATI chip, the VRM, and the tuner casing. This didn't really
do the job, so I proceeded to stick them on every available flat
surface near a hot spot spot on each side of the card.
RAM sinks on the component side of
the TV card...
...and on the solder side.
Next, I installed this porcupine in the system.
TV card and its heat sinks in the
system.
It was now time to tackle the video card and the Condor.
Aerocase is a very small company that currently builds each
heat sink to order. This became evident to me when I phoned the company
to confirm my order (they didn't have an automated e-mail system)
and the president took my call. She was very interested in how I
intended
to use the reverse-wing Condor, and we had a pleasant chat while I
explained my tentative plan.
When the package arrived a couple of weeks later, it contained
a
slip of paper informing me that my heat sink had been randomly selected
for post-assembly testing, and might appear used. It was true: there
were several scratches on the heat pipes and a couple of fins were
bent. The heat block also had about five times as much Arctic Silver 5
on it as needed. After cleaning this off and putting a fresh dab onto
the GPU, I was ready to install the heat sink on the 7900GT card.
First I had to bend the heat pipes back to 90 degrees. They
had been
bent, apparently during packing or shipping, to about 110 degrees. A
little gentle pressure did the trick. Next, I had to thread the
supplied bolts through the video card into the embedded nuts in the
Condor heat block. The instructions were helpful, if a bit down-home:
put the heat block on a coffee cup, insert the toothpicks, add the
rubber spacers, then lower the video card onto the heat block using the
toothpicks as guides. This worked okay, but one of the four nuts did
not line up with the corresponding hole in the video card; it was off
by a fraction of a millimeter. Using a bit of (careful!) force, I was
able to thread all four bolts.
This revealed the next issue: the supplied red rubber washers
were
much too thin to cushion the heat block on top of the GPU. Here's a
picture showing this:
The red washers are too thin for
this video card.
I had to very carefully tighten the bolts in a diagonal
pattern to
squeeze the heat block onto the GPU without breaking anything. (What
looks like a warp in the above picture is a lens artifact; the board is
flat.) This cooler is defnitely not for the uninitiated.
Here is what the final assembly looks like.
Video card with Condor mounted.
The uneven spacing of the wing parts is evidence of hand
assembly.
Perhaps the perfect alignment and spacing of Thermalright and Scythe
heat sinks has
spoiled me. Of course none of this has any effect on the actual
performance of the heat sink.
(Note there are no RAMsinks on the board. I used to be a big
believer in these, which is why I had so many available to put on the
TV card. However, as part of the Condor discussion on SPCR (page
4), it was pointed out that GDDR3 chips don't get hot. It's
true: the
DRAMs on my card don't get much hotter than the card itself. That
discussion also pointed to this article,
where a gonzo overclocker used a phase change system to supercool his
GDDR3 and got no speedup.)
The 7900GT with the Condor attached fit nicely into the P180, and wrapped around the TV card as expected.
Condor in the system, wrapped
around the TV card.
By happy accident, the Condor radiator lines up nearly
perfectly
with the rectangular vent in the back of the case originally
intended for the ill-fated GPU duct/box/thing that came with the early
P180s. The warm air exhaust for the video/TV chamber is
comprised of the rectangular vent along with the two holes created by removing the PCI slot covers from above and below the TV card. Note that my case has the old-style solid PCI covers, which I think do a better job of directing air flow than the new-style perforated blanks. Here is a view of the exhaust holes.
Hot air from the Condor and the
TV card goes straight out the back of the case.
The next job was to install a fan to blow fresh air into the
video
chamber. My first attempt was with an Aerocool Streamliner 14cm fan.
This fan fit the opening very well, and I thought its extra large size
would make it quiet and efficient. Unfortunately it was neither. It
moved less air than a Nexus, and was considerably louder.
So even though it didn't fit as well, I installed a Nexus fan
near
the upper disk cage. The cage is still present, but its caddies have
been removed, as seen here:
Video fan nestled among
connectors and cables.
Although it looks a bit cluttered in the above photo, the air
flow
is almost entirely unobstructed. The fan is sitting down on the blue
IDE connector, wedged between the SATA connector and the drive cage.
The various power cables hold it mostly in place, and the single cable
tie to a taut power cable secures it firmly.
The top side of the video chamber is formed by a single large
flat panel that runs the full length and depth of the chamber.
This large panel forms the top of
the video air flow chamber.
I added the quarter to give the camera something to focus on,
but
also to give an idea of just how big this panel is. The cut notches at
the bottom are to accommodate various chips, capacitors and connectors
on the motherboard. The tab near the center of the bottom edge is a
vertical spacer that rests against the video card motherboard
connector to hold the panel above the card.
Installed in the system, the panel looks like this:
The video chamber, nearly done.
The spacer tab can be seen in the above photo holding the far
edge
up. To the right of that, the panel is threaded between the DIMM
handles and the top of the fan, which hold that end snugly. The left
edge butts against some foam at the top of the exhaust opening. The
close edge is sealed off and held in place by some foam attached to the
case side panel.
The final task was to seal the area around the fan. Two layers of thick foam, one full-length and the other shorter, took care of that:
Foam seal added to the video fan
completes the chamber.
So with one fan, one baffle, a monster heat sink, and some
copper and foam, the middle section of the system is taken care of.
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