Did you clear the CMOS afterward?
How To Clear CMOS (Reset BIOS)
Also, make sure the RAM is properly seated. Check all other hardware while you are looking inside the system, as well. Follow these steps for ESD safety:
- Shut down and turn off your computer.
- Unplug all power supplies to the computer (AC Power then battery for laptops, AC power for desktops)
- Hold down the power button for 30 seconds to close the circuit and ensure all power drains from components.
- Make sure you are grounded by using proper grounding techniques, i.e. work on an anti-static workbench, anti-static desk, or an anti-static pad. Hold something metallic while touching it to the anti-static surface, or use an anti-static wristband to attach to the anti-static material while working.
Once these steps have been followed, it is safe to remove and replace components within your computer.