i am having 815e motherboard, i disabled the on board sound and installed a creative sbpci card, i already had windows in my system,when i installed redhat linux 8 the pci card became inactive and on board sound became active, but in windows the pci card is active, how can i make linux detect the creative sound card?

Try disabling plug and play in the BIOS. You could also run as root:

lspci -v

to get all the information about your PCI devices. Once you've got your plug and play disabled, you should be able to run

modprobe <module name>

but replace <module name> with the correct driver/module for your sound card and get rid of the <>. This should get your soundcard to work. AFter that, you'll need to add

alias sound-slot-0 <module name>

to your /etc/modules.conf file using your favorite text editor. You should also uncomment (remove the # sign from the beginning of) the line in your /etc/rc.d/rc.modules file that says:

/sbin/modprobe <module name>

again substituting the correct module name and removing the <>. Hope this helps.