hello,
Please am having a problem with my two memories (256 each). my pc doesn't go past the black startup screen and so i removed one and it worked then said no hard disk found. went into bios and pressed F3 to detect the drives and it detected and booted and i was able to get into my os. but now my pc is soo slow please does anyone know why am having a memory failure, could it be that the cmos battery is failing ? thanks

The memory chip is faulty all you is to buy another one.

get another memory chip, replace it on your pc mainboard. startup pc, enter setup, press (f7 or f9) depending on product maker. change boot sequence, save & exit. that's all

well if re-seating your memory chips doesn't work, then u might need new chips but first, change your cmos battery, then change your IDE cables. try to remember the last changes u made to your system b4 the problem started and see if reversing the changes solves your problem. when all fails get new memory chips.