Try these generic fixes:
- move your RAM stick to another slot
- download MemTest and do an extended test on your RAM. Caution: it'll take several hours
- do a BIOS reset by talking out the motherboard battery. Be sure to leave it at least one minute with the power cord unplugged from the PSU
It is possible that your video card might have caused some damage to your RAM. Hope I'm mistaken.
For the time being try the above and post here what you accomplished.
Too late I'm afraid.