Green power light blinking thrice repeatedly, PSU and CPU fans spinning, red HDD LED lights up once then never comes back

[arun.the.kid77]

i3 cpu, zeb 450w psu, 160 gb Samsung hdd, lg dvd drive.

Green power light blinking thrice repeatedly, PSU and CPU fans spinning motherboard light on steady green, red HDD LED lights up once, goes off and then never comes back unless i unplug and replug.

 

[arun.the.kid77]

Reseat the RAM.

Three blinks/beeps almost always mean RAM problem