Before trying to quiet an older pc I tried adding some memory. It had a pair of 256Mb chips in slots 1 and 2 and I added a 1Gb chip to slot three. Turn it on and nothing. Removed the 1Gb chip and nothing. Power supply fires up and fans run but motherboard diagnostic leds are green green green red which according to the manual is the real time clock. I upgraded memory many times before without issue so I'm a bit bummed. Have I permanently quieted this system? Any gurus have any advice? Thanks in advance.