After the jumper has been placed on PINs 2-3 for several seconds it should be returned to pins 1-2.
The beeping is telling you that there is something wrong. The beeps you describe points to a problem with RAM. What is the make and model of the memory module(s)?
Did you connect the 4 pin 12 Volt cable from the power supply to the connector labeled 25 in the manual?
What video card is being used in this build? A single short beep is usually heard as the first and only beep when the video card has passed its power on self test. After this initial beep you should be able to see something on the monitor.
What happens to the beep code when there's no memory modules installed? Does it change?
Ya, I don't think the problem is with the bios.
I use a Patriot 1GB DDR2 800 Stick that I took from another working computer,
So it Should be fine. (I don't have other DDR2 chips to check now)
I use the internal Video Connector ( I think it's X300 Chip), and no short beeps
only long ones
Like ko888 said, if you are getting a continuous series of long beeps, you have a RAM problem. It could be the memory. It could also be a problem with the motherboard: RAM sockets, memory controller, even the power regulator for the RAM. It does the same thing that the CPU power regulator does. It steps (not quite accurate, but close enough) the 3.3 volts from the PSU down to around 2 volts.
If you are getting the same beeps with known good RAM (works in another system), try changing the motherboard.