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SPCR Article
Oct 2, 2006 by Chris Thomson (cmthomson at comcast dot net)
Chris
has been a
computer system architect at Myrias Research,
Amdahl, 3Com, Nokia and others for the last 20+ years. An ex-pat
Canadian, he now resides in sunny Pleasanton, CA. Chris used
to think that people who build their own PCs and then overclock them
are nuts. Over the last year or so, he's become convinced of it.
Chris caught the silent PC bug while building a hot Pentium D 830 dual-core system a
year ago, and has become an active SPCR member. This article describes a complete upgrade to an overclocked Core 2 Duo system that is quiet enough to make his laptop PC seem outrageously loud.
* * *
TIME FOR AN
UPGRADE
After my excruciating effort to quietly cool the 150W space
heater
marketed under the moniker Pentium
D 830 (documented on SPCR in two
parts, Quiet
DIY OC'ed Pentium D 830 System and Quiet
DIY OC'ed Pentium D 830 System, Part Two),
California summer arrived, and the temperature-controlled fans in my
system kept going faster and faster and got noisier and noisier. I
started to get antsy about upgrading my system to the next generation
CPU, both for lower wattage and for better performance.
In the last year, three major events have impacted
quiet high-performance PCs: the introduction of the Core
2 Duo "Conroe"
CPUs from Intel, the relentless race by video card GPU vendors for
higher performance regardless of power consumption, and the catch-up
race of heat sink vendors to cool those GPUs. Two good, one not so good.
Of these, the Conroe is probably the most significant. Not
only
is the power consumption far lower (as much as a 2/3 reduction), but
the performance has been boosted substantially, particularly for audio
and video transcoding, the most common compute-bound tasks I do. This
is because the cache is very large (4 MB on the E6600) and the
execution units have twice as many SSE stations as previous CPU cores.
The "core" of my upgrade.
The performance increase in GPUs is also impressive: the newer
7900GT
outperforms my old X800XL by almost 2:1, and it is not even a top
performer anymore. It is, however, a very good compromise of
performance, price, and power consumption.
Time has marched on for memories as well. My old 5400C4 memory
was
looking pretty sad next to newer 6400C3 sticks. Even my old DVD writer
was looking tired. And of course it was time to replace that CRT with
an LCD.
In revamping my system, I set the bar high for myself: a
system at least twice as fast as the
old one, and so quiet it couldn't be heard at 6am on Sunday. By
starting with a large well-damped case, using
gigantic heat sinks and very slow fans, minimizing the system airflow
impedance, ducting hot air directly
out of the box, and overclocking fast components to almost
overload the heat sinks, I was completely successful.
MY NEW SYSTEM CONFIGURATION
As the old carpenter said: "I've had that same hammer for 25
years, although I've gone through four handles and two heads." I still have the same system, it just has a new CPU,
motherboard,
memory, video card, DVD burner and monitor. Here is the complete
configuration:
- Antec P180 case (the original silver/black one)
- Antec Phantom 500 semi-fanless power supply
- Intel Core 2 Duo E6600 CPU
- Asus P5W DH Deluxe motherboard
- 2 GB G.Skill F2-6400PHU2-2GBHZ memory
- eVGA 7900 GT KO SC (N567) video card
- ATI TV Wonder Elite TV card
- Samsung 244T 24" LCD monitor
- two Samsung SpinPoint SP2004C 200-GB SATA disks
- Sony DRU820A DVD burner
- generic floppy drive
- Scythe Ninja CPU heat sink
- Thernalright HR-05 north bridge heat sink
- Aerocase Condor GPU heat sink
- Swiftech MC14 copper RAMsinks
- Scythe Kama Bay filtered air inlet
- Nexus Real Silent 120mm orange fans
- Noise Magic NMT-3 temperature-sensitive fan controllers
- AcoustiPack foam
- home made styrene ducts and baffles
- various peripherals (UPS, printer, zip drive, speakers,
keyboard, mouse, etc)
| In
the rest of this
article, I'm going to document the system as
though it had been built from scratch. In actuality, most parts were
carried forward unmodified from my old 830D configuration. Most of the
concepts are also documented in my earlier 830D articles, along with
credits to SPCR members who suggested them. |
COOLING THE CPU, NB
& VRM: THE FANTASY
The E6600 is rated at 65W TDP (thermal design point), and
actually
consumes closer to 55W. I knew that cooling it would be
straightforward, but experience
with my old 830D/P5LD2 configuration left me concerned about
cooling the motherboard components, especially the Vcore VRM (voltage
regulator module). And of course the 95W video card would need some
attention.
Two of the new Conroe-ready motherboards caught my eye: the
Gigabit
GA-965P-DQ6 and the Asus
P5W DH Deluxe. Both feature heat pipes from
the north bridge to radiators near the CPU, as well as radiators for
the VRM MOSFETs, also near the CPU. In addition to good VRM cooling,
these boards also use highly efficient multiphase VRMs (12 and 8 phase,
respectively).
This made me think that I could cool the CPU with a
Thermalright
XP-120 heat sink with the fan blowing up from the
motherboard, which
would force cool air through those north bridge and VRM radiators. I
would then duct the warm air straight out one of the case holes. This
would eliminate the need for a case fan, since the motherboard and CPU
would be sharing a fan. The video and TV cards would be cooled
separately.
I initially tried the DQ6 motherboard, but it was not a happy
experience. The 965P north bridge actually has fewer features than the
945P on my old motherboard, and would not allow me to directly control
the DRAM parameters. Also the BIOS is set up for overvolting and
overclocking only; it is not possible to set voltages directly, or
below the stock values called for by the VID and SPD. I ended up
selling the board and switching to the P5W DH, which uses a 975X north
bridge and has the features I wanted.
With the P5W DH, the XP-120 can be mounted in the "standard"
orientation, with the heat pipe bends toward the DIMMs, or rotated with
them facing the top of the case. The latter is better, as it provides a
larger space between the heat sink and the case outlet, allowing for a
larger duct with smoother bends. It is also easier to mount in this
direction because there is more room around the clips. Here is what the
XP-120 looked like installed in the P180.
XP-120 CPU heat sink mounted on
the P5W DH inside the P180 case.
Note how the heat sink lines up quite well with the hole in
the
case. I never actually built the duct, but it would have been quite
simple. Note also that I ran the CPU power cable under the motherboard.
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