Did you install the chipset drivers as the first 2 drivers installed after loading Win 7 on the new SSD? Without the chipset drivers, the NIC driver may not install or may not work.
If you didn't install those, download them on any PC and copy them onto the desktop of the 8300 using a USB stick. Reboot in Safe Mode (reboot and press F8) and install the Chipset Software Installation Utility H67 driver first and then the AMT HECI driver. Then reboot normally and install the Broadcom NIC driver. Reboot when that's done.