IT & Computers (5)

Julien ARNAUD

Everyday laptop, and computer history

Until around 2007 [0], I was a big fan of powerful desktops as my daily driver. At that point my computer was liquid-cooled PowerMac G5 Quad 2.5 Ghz. This was a beast and I loved it. I then switched to a MacBook Pro 15" Penryn complemented by a NAS to compensate for lack of local storage. I kept on the laptop + NAS train for a while : more recently with availability of 4TB SSDs I went to a laptop-only setup. My previous laptop was the IdeaPad Pro 5 (5800U,…

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Julien ARNAUD

Machine learning desktop

I built a new computer to play with some machine learning. It uses what seems to be the best scoring case for airflow and temperature : Fractal Torrent Compact. The full setup is : The 4090 is capped to 65% TDP as going any further quickly hits drastrictly diminishing returns (anything above 75% should be considered OC). When capped, the card only runs at about 60° ! That thing really is a crazy object and product. During training the computer draws about 400W at the wall. Which sits perfectly in…

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Julien ARNAUD

US-48-500W power supply repair

One of our US-48-500W died at work. Since Ubiquiti has bumped the price and shifted the range quite a lot, I decided to repair it to keep it as a spare. I first confirmed that the PSU was the culprit by powering the switch with my lab PSU. Using a meanwell PSU (RD-125-2448) providing both 24V and 48V rails ,we don't reach the original 500W of PoE power, but that's still enough for our needs (some phones, cameras, and access points). I didn't put much efforts into PSU placement in…

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Julien ARNAUD

Blocking hard drive I/O with sound

I replicated the results of Connor Bolton, Sara Rampazzi, Chaohao Li, Andrew Kwong, Wenyuan Xu and Kevin Fu. in "Blue Note: How intentional acoutic interference Damages availability and integrity in hard disk drives and operating systems". I set up one of my DIY Cabasse Spheres in front of a Fujitsu MJA2160BH. Doing a frequency sweep from 850Hz to 1.1Khz at around 102 to 105dB. When reaching close to 975Hz +/- 25Hz, the bitrate of the read file drops from 70MiB/s to a few KiB/s. Data was generated from /dev/random, secondary…

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Julien ARNAUD

Motion simracing rig

Components Intel i7 7700K 16 GB DDR4 512 GB NVMe 2x nvidia GTX 1080 in SLI 750 W Corsair PSU 3x 43" 4K TVs (11520 x 2160 px) ProSimu T1000 2DOF Fanatec Clubsport 2.5 Wheel base ClubSport Wheel Rim SPARCO® Rally ClubSport Porsche 918 Wheel ClubSport Steering Wheel F1® Esports V2 Fanatec Clubsport V3 Pedals Fanatec ClubSport Shifter SQ V 1.5 4.0 audio using 2x 8" Samson Resolv A8 active monitors (front) 2x 6" Samson Resolv A6 active monitors (rear) The whole system draws about 460W idle, and around 700W…

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