|1st of all, most of the helpers in this forum, myself included, HATE it when someone refers to their computer as a CPU. Your CPU is a Pentium E2160. You can NOT connect RAM or a hard drive to a CPU...the RAM & hard drive connect to the motherboard.|
2nd, you do NOT need a hard drive to boot a system & get a display. Your hard drive is NOT the problem. And the fact that you're getting beeps means that the motherboard & CPU are most likely good. As the beep code link states, the problem is the RAM.
Here are your system specs:
Being that your CPU is a Pentium E2160 which runs at 800MHz FSB, you *should* be using DDR2-800 RAM. You can use others (DDR2-533, DDR2-667) but performance will suffer slightly. However, whichever RAM you use MUST be spec'd out to run at 1.8v. If you have "performance RAM" or "gaming RAM" that's spec'd for 2.0v or higher, you shouldn't expect it to work in your OEM system.
Strip your system down to the bare minimum needed to boot & access the BIOS. That means: disconnect all drives (floppy, CD & HDD...both the power & data cables), unplug all external devices except the monitor & keyboard. If you have a video card, remove it & connect the monitor to the onboard video. If you have any additional cards (sound, LAN, USB, etc), remove them. And install just ONE stick of RAM making 100% sure it's fully seated in it's slot & securely locked in place. Before attempting to fire up the system, reset the BIOS using the clear CMOS jumper (make sure the power cord is unplugged before doing so). Now try to boot up...still getting a beep code?