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OVERCLOCKING THE SYSTEM
The Conroe family is very overclock-friendly, as are the new
motherboards and memories. Reports of overclocks of 50% or more are not
uncommon on the enthusiast forums.
The latest generation of CPUs require new test and stress
software. Older programs such as CPU
Burnin, CPUburn,
and Prime95
do not load the CPU fully. The new gold standard for CPU, north bridge
and memory stability is ORTHOS,
which runs two copies of Prime95 with varying parameters, while the
best CPU load program for Core 2 or Core CPUs is TAT (Thermal Analysis
Tool), which is a proprietary Intel program that can be downloaded
through links in this
thread. The best video card stress tools continue to be rthdribl
and ATI
Tool.
ATI Tool works with both ATI and nVidia GPUs, and consumes slightly
more power in tumbling block mode than in artifact check mode.
Running TAT at 100% on both CPUs, the core
temperature of the E6600 at
stock frequency and voltage (2.400 GHz and 1.35V) goes up to only 68C
with the Ninja fan running at just 600 RPM. If you're not overclocking
this CPU, you really don't need the kind of cooling described above.
However,
since my plan all along had been to overclock to the maximum frequency
supported by quiet cooling, this temperature serves only as a
comparison point.
I started my overclocking with the memory. The G.Skill HZ
memory is
hand-picked to support high clock rates and low latencies at elevated
voltages. The highest reliable frequency I found for this motherboard
and
memory was 740 MHz 3-3-3-12 at 2.3V, or 812
MHz 4-4-4-12
at 2.4V. As usual, the memory is not the limiting factor in my
system clocking.
Initially, I had a week 24 CPU (the first week of production),
which
required a relatively high Vcore to overclock. My initial target for
fan speeds was 700 RPM, which is very quiet but still audible. I was
able to overclock to 3.244 GHz, but only at rather low ambient
temperatures.
Later I got a week 28
CPU, which overclocks well at noticeably lower voltages. With this
newer CPU, I was able to run the system with FSB
and DRAM frequencies of 361 and 722 MHz, and DRAM, CPU and north bridge
voltages of 2.30, 1.4625 and 1.55. The DRAM parameters were set to
3-3-3-12-5, and C1 Enhanced, SpeedStep and Hyper Path 3 were disabled.
This ran the CPU at 3.252 GHz, and was completely stable with the fans
running at only 600 RPM.
Getting the last few drops of performance required adjusting
the tRD memory parameter. This parameter is not user-settable in the
BIOS, which silently sets it to 5 when the other parameters are 1:1 and
3-3-3-12-5. Changing it to 6 with memset
3.0 made my system stable with FSB and DRAM clocks of 370 and
740. This runs the CPU at 3.333 GHz. To achieve complete stability, I
had to overvolt the DRAM, CPU and north bridge to 2.30, 1.50 and 1.55
volts. Higher overclocks are possible, but only with faster fan
settings. I was so pleased with the inaudibility of 600 RPM that I
decided to stick with that.
Recent versions of the BIOS disable CPU auto throttling
(called thermal control in the user interface) by default. If you want
your CPU to
last very long, it is imperative that you enable this feature in the
BIOS, or that you always run RMClock
to provide throttling. I let the BIOS control it.
eVGA sells many variants of the 7900GT video card. The N567 7900
KO SC
(KnockOut SuperClocked) is overclocked at the factory to run the GPU
and GRAM at 580 and 790 MHz. As with any nVidia card, to display or
modify this clocking, you must install the CoolBits registry hack,
available here.
To achieve this clock rate, the GPU is overvolted from 1.2V to 1.4V
when running 3D applications, which causes it to consume much more
power than a standard 7900GT. After several experiments I was able to
increase this overclock only slightly; in the end, I reverted to the
factory settings.
I ran a bunch of benchmarks to compare my final overclock with the
stock CPU and memory settings, and also, as much as possible, to my old
830D system.
|
Benchmark
|
Stock E6600 |
OC E6600 |
OC 830D |
| FSB, DRAM, CPU clocks |
267, 333, 2.404
|
370, 740, 3.333
|
235, 627, 3.532
|
| Video GPU, DRAM clocks |
580, 790 (1580)
|
580, 790 (1580)
|
427, 555 (1110)
|
| DRAM latencies |
5-5-5-12-9
|
3-3-3-12-5
|
4-4-4-12-4
|
| Sandra iSSE, fpSSE |
132345, 71415
|
184027, 99278
|
35260, 40143 est
|
| Sandra RAM bandwidth: int, fp |
5204, 5215
|
7214, 7226
|
5820 est
|
| Sandra memory latency |
90 ns
|
61 ns
|
-
|
| 3DMark05, 3DMark06 |
10134, 5609
|
10406, 5911
|
5379, -
|
| PCMark04 CPU, memory, graphics, disk |
-
|
-, -, 11273, 12307, 4830
|
6999, 5569, 6795, 4372
|
| PCMark05 CPU, memory, graphics, disk |
6082, 5165, 8283, 4246
|
8472, 7249, 9104, 4256
|
-
|
| PCMark04, PCMark05 system |
-, 6580
|
-, 8180
|
7114, -
|
This system is very quick. Note the outstanding SSE scores; this
system encodes video over three times faster than my old one. Its video
FPS rate is nearly twice as fast.
FINALLY, SETTING FAN SPEEDS
As hinted many times above, I run my fans very slowly.
The Ninja is a truly exceptional heat sink. Even with the CPU
consuming 100W at this extreme overclock, and the fan spinning at an
inaudible 600 RPM, the cores stay well below throttling under my
heaviest realistic workload (video recoding plus protein folding). This
workload corresponds to 75% loading in TAT. With faster fan settings it
is possible to avoid throttling even under the synthetic workloads, but
I stuck with 600 RPM since it was all I needed. Because various programs report throttling temperatures varying from
83C to 97C, I can't say with any precision what my actual CPU
temperature is.
The Condor cools the GPU very well, needing only a slight
draft to shed its heat. I ran a series of fan speed tests loading the GPU with
the ATI Tool artifact scanner. This provides a higher load than any
game I'm aware of, though slightly less load than rthdribl. I used
SpeedFan to adjust the voltage to the Nexus fan installed in the video
chamber, and measured both the GPU and south bridge steady-state
temperatures. The ambient temperature was 22C.
| Nexus 120 Fan in Video Card Chamber |
|
SpeedFan %
|
44
|
50
|
55
|
60
|
65
|
70
|
75
|
80
|
|
Fan RPM
|
598
|
670
|
721
|
774
|
830
|
870
|
917
|
970
|
|
GPU - °C
|
105
|
104
|
98
|
94
|
94
|
92
|
89
|
88
|
|
SB - °C
|
43
|
43
|
41
|
40
|
39
|
39
|
38
|
37
|
The fan becomes barely audible at about 650 RPM, although it
is very quiet by most people's standards even at 1000 RPM. In this
setup, there is no reason to run the fan faster than about 750 RPM. The
default throttling temperature for this GPU is 130C, so none of the
temperatures here are particularly excessive.
Nonetheless, in order to keep the GPU below 100C, I ultimately
decided to let the fan run faster under load. I set SpeedFan to use a
minimum of 44%, a maximum of 55%, and a desired south bridge
temperature of 42C. The only time the fan speeds up is during
benchmarks.
The P5W DH has five fan headers: CPU, CHA1, CHA2, PWR1 and
PWR2. As the naming implies, these form three groups from SpeedFan's
perspective: CPU, CHA and PWR. I used one of the PWR headers to control
the top case fan, and the two CHA headers to control the video and
power supply/hard disk fans. The top case fan and the power supply fan
have NMT-3 controllers; these work well in combination with SpeedFan
and slow these fans even more when temperatures are low.
I set the CPU fan to 43%, the top case fan to 44%, and the
video and PS/HD fan to 44-55% depending on the MB temperature. When the
ambient is 22C and I'm folding, the fans run at 580, 590, 590 and 480
RPM. They speed up a bit when the room is warmer, typically 20 RPM. The
hard disks stay below 40C, and the power supply fan never spins up.
How quiet is this system? Well, if the DVD isn't spinning and
the hard disks aren't seeking, the only perceptible sound is the faint
hum of the LCD power supply echoing off the wall six feet away.
Obviously the house and neighborhood must be totally quiet to hear
this. By comparison, my company laptop is outrageously loud.
* * *
Articles of Related Interest
Quiet DIY OC'ed Pentium D 830 System, Part Two
Quiet OC'ed Pentium D 830 System
Quiet PC for Torrid Thailand
Doug's Quiet Wood Case PC
* * *
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