|i have tried to swap the cmos battery and memory|
Neither of those failing would cause the monitor to give no display.
It's most likely one of these:
a) the signal-cable from monitor to PC
b) the graphics card inside the PC
c) the monitor itself
If a new signal-cable makes no difference, and the monitor works okay on a different (known working) PC, you'll need to replace the graphics card.
it needs to be one that fits into either:
a) a PCI slot
b) a PCI-Express x16 slot
The pavilion s3000 only has one slot of each type, so if other cards have been fitted since it was bought new, you'll need to check which slot is empty.
PCI slot is usually white.
PCI-E x16 slot is usually black.
Although with an HP motherboard anything is possible colour-wise.