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The LAN9512 data sheet (http://www.smsc.com/media/Downloads_Public/Data_Sheets/<br />
9512.pdf) in Table 4.1 on p.40 says it comes in two versions, rated for operation at an<br />
ambient temperature in still air (Ta) of 70 C (commercial) or 85 C (industrial). It uses 763<br />
mW at 3.3V with maximum traffic on 100baseT and both USB ports (Table 4.3.4, p. 42).<br />
There is a study of RasPi heat profiles by "Remy" at ¿Se calienta el ordenador Raspberry<br />
Pi? Estudio de sus temperaturas en funcionamiento (http://www.geektopia.es/es/<br />
technology/2012/06/22/articulos/se-calienta-el-ordenador-raspberry-pi-estudio-de-sustemperaturas-en-funcionamiento.html)<br />
(Is the Raspberry Pi computer getting hot? A<br />
study of its operational temperature.) The Spanish article has numerous color<br />
temperature images of RasPi in various operational modes, with the highest LAN9512<br />
case temperature measured as 64.5 C.<br />
Networking no longer works when changing <strong>SD</strong> card between two<br />
Raspberry Pis<br />
In some distributions, /etc/udev/rules.d/70-persistent-net.rules remembers which MAC<br />
address is associated with eth0, so each new device will be assigned as a different<br />
interface (eth1, eth2, etc.) due to the different MAC addresses. Editing /etc/udev/rules.d/<br />
70-persistent-net.rules to remove the invalid rules and rebooting may help fix the<br />
problem.<br />
Crashes occur with high network load<br />
The USB driver allocates memory from the kernel, and when traffic is very high (e.g.<br />
when using torrents/newsgroup downloads) this memory can be exhausted causing<br />
crashes/hangs. You should have a line like:<br />
vm.min_free_kbytes = 8192<br />
in /etc/sysctl.conf. Try increasing that number to 16384 (or higher). If that doesn't work,<br />
try adding to /boot/cmdline.txt<br />
smsc95xx.turbo_mode=N<br />
which will reduce network throughput, but has improved stability issues for some.<br />
Network connection fails when a Graphical User Interface is being used<br />
The network connection may fail when the command startx is used to enter a Graphical<br />
User Interface. This is caused by a bug in the USB driver related to certain types of USB<br />
mouse.
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