Have you any idea to prevent backaches from long sitting on Computer Chairs

The chair you use isn't so much the issue as your leg position. Try proping your legs up on a small stool, or at least alternating propping up one leg at a time at intervals. Also, make sure your computer screen is positioned so that you don't have to lean forward to read it. If you need to move it foward in order to make our seating more comfortable, then try that. Same thing with the keyboard. If it needs to be repositioned so that you are not slumping over when you are typing, then raise it up as needed. Lastly, trying getting up once an hour for a few seconds just to stretch a bit, then return to your work.

Yes, i work form morning till night just sitting right in front of computer. So if you want to prevent backaches, just put a small pillow on your back and this will reduce your backache, as well as let you sit more comfortable.

I get out of my chair for a few minutes every hour and do some stretching, so my body doesn't ache. Make sure you have plenty of beverages, as you will feel better when you drink enough fluids. I drink several glasses of water while working each day.

I sit in front of a computer at least 8 hours a day and a maximum of 16 hours but I don't have backaches...yet. I would realize that I have been sitting in front of the computer for too long when I could not longer focus and the things started that I am reading started to get blurred. It is indeed very important to have a very comfortable chair and table that is the right height for you. My computer chair has very good back support that when I lean, it feels as if my back is being massaged.LOL!. Posture is also important in keeping backeaches away.