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Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

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Lepl parser for Python.

Colorless Green.

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SVG experiment.

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Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

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Overclocking Q9550 with Asus P5Q

From: andrew cooke <andrew@...>

Date: Thu, 3 Sep 2009 09:37:55 -0400

I decided to buy a new CPU while socket 775 chips were still available
(tech supplies here in Chile are a bit intermittent at times; also I
may be wrong about this, but my impression is that the new Intel stuff
is not going to work with the hardware I have, and anyway I want to
switch to AMD in the longer term to avoid supporting Israel-based
companies).

The Q9650 seems to be the top model available, but Q9550 is
significantly better value for money - the only difference is a
slightly smaller multiplier (8.5 v 9).  Both are quad core with 12MB
L2 memory.  So I went with the Q9550.

At first, I had a world of pain with memory errors.  I finally tracked
it down to having two slightly different sets of DIMMs.  Even though
all 4 have the same part number, two have slightly different chips to
the other two, and I wasn't using the matching pairs in the "same
colour" slots on the mobo.  With that sorted, everything is looking
good.

Initial results with memtest using only minimal changes to the mobo
config (change FSB and select memory) give me a stable system (no
memory errors with memtest) at FSB of 452 MHz (CPU 3.8GHz, memory
DDR900) and errors at FSB 461MHz.

This is with air cooling using a Zalman CNPS9500 AT fan on the CPU -
the limit seems to be the memory rather than the CPU (which, unloaded,
is sitting at around 50C according to lm_sensors).

Andrew

Faster with Overvoltage

From: andrew cooke <andrew@...>

Date: Fri, 4 Sep 2009 07:21:57 -0400

Increasing the memory voltage to 1.94V I can get to an FSB of 461 with
5-5-5-15 timing.  That means a 3.92GHz processor with DDR922 memory.

Unfortunately I still get errors at 470 FSB, which is what I would
need to hit 4GHz.  I've played with various BIOS settings related to
DRAM, but nothing is getting me the extra distance and I don't want to
increase voltage further (the DIMMs are surprisingly hot to the touch
as it is).

(If the numbers seem a bit odd it's because I'm using bisectinon
searches, so the speed is between 400 and 470, mid point 435, then
quarter point 461, while the voltage is between 1.8 and 2.1, midpoint
1.95, but the mobo uses 0.2V steps).

Andrew

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