Gigabyte P35 DS3P onboard lan only 10 Mbps

Had another 'random' thought... Are you overclocking at all? If you'll look at the "MB Intelligent Tweaker(M.I.T.)", you'll see an entry for "PCI Express Frequency (Mhz)", which defaults to "Auto". While the manual states "Auto sets the PCIe clock frequency to standard 100 MHz", this is not quite true. It would appear that in auto, this setting is taken from some kind of internal divider, and if the system clock is changed, it causes the PCIe frequency to vary, as well. On the socket 775 MOBOs, you always want to set this to "100" and not "Auto"; the LAN chip is 'hung off' the PCIe bus, and if the frequncy goes up, it is generally the first thing to suffer - either behaving erratically, or, 'dropping off the bus' completely. This is an issue for socket 1366/i7/X58 boards, as boosting the frequncy of the PCIe bus somewhat is, for no reason I've ever seen a physical explanation regarding, key to getting high, stable overclocks with these platforms - but - the LAN chip 'waves goodbye' somewhere slightly above 105 to 108, and, past 110 or 112, most video cards 'check out' as well. I occasionally see this problem when people 'bump up' this setting, thinking it will make their video card(s) faster, (which it doesn't - just adds to their instability), and manage to 'crank' something else off the bus...