Boot Issues : Asus P5B Deluxe

Try unplugging the PSU. If that has no effect, I would reset the CMOS jumper and default the BIOS. If that doesn't work you will likely have to have spare parts like RAM, CPU, HD, etc. to troubleshoot any further. HTH.

you say that you are getting no sound at all,not even the bios beep???
well then ,,it seems like that either your ram [mabey] or cpu [very rarely] has gone south,if it was me i would disconnect my hdd'[s] get out a bootable floppy and try and see if it will boot whilst testing the ram stick[s] separately,no sense booting repeatedly at the hdd[s] for nothing or not having a floppy drive,install memtest on a bootable usb stick and test the ram,you have checked all ,and i mean all ,,, the connections inside your
computer,,you must be absolutly certian that everything is "A ok",,otherwise you might waste time and a lot of effort for nothing because some little detail was overlooked,all else being equal your main areas of concern would seem to be the psu,the cpu,and the ram,and the key there is a good quality psu,no crap allowed,this the most important single component in any computer,for obvious reasons..

Thanks Dokk, yeah I am not able to hear the bios beep. I am using Antec True power 550 watt PSU so I guess on that front I am ok. Only thing I am using 2 sticks of corsair xms2 ddr2 800MHz ram (CM2X1024-6400). Don't know whether that can be an issue or not. But this combo worked for last 1 year. If I could get mobo to post atleast I could have tried memtest etc , which I am not able to do. I tried reconnecting all the connections, cleaned ram contact points, but none seems make my mobo to post , duh