I have found the 0404 BIOS to be very good on the P5K Deluxe. Still, you shouldn't be having this problem with any BIOS. Reset the CMOS BIOS by
1. unplug PC from the wall, hit power switch to discharge residual elec.
2. remove the battery
3. move the clrtc jumper from pins 1&2 to 2&3, let it sit for a few seconds and then put the jumper back on pins 1&2.
4. replace the battery
5. plug the PC back into the wall, reboot, enter BIOS and set boot order.
You can try disabling Legacy USB as well. Don't use Q-Fan.
If that doesn't help, try a barebones setup as per the below guide:
This is a little guide I made up for doing a barebones setup. It is a great troubleshooting tool that all of us need to use at one time or another. If you can see any changes that will improve this guide, or the procedure, then please post them as this is a work in progress.
BAREBONES SETUP
You are going to have to do a barebones setup and test each component. This will read a lot harder than it actually is. The initial procedure takes only around 10-15 minutes. The follow on troubleshooting may take a lot longer though. Also, please do not skip steps. Do everything in order and as listed or your troubleshooting will be flawed.
Caution: Please remember that turning a PC off does not mean there is no power going through it. Modern systems maintain a trickle of power to keep the standby functions running. You either have to turn off the switch on the Power Supply Unit (PSU) itself or unplug the system from the wall. Unplugging is best. If the green LED on the mobo is lighted you have power to the board. Make sure it is out before proceeding. Also, be aware of static. Make sure you wear an ESD strap or discharge yourself on a steel part of the case before touching anything inside.
First, unplug the PC from the wall and then push the power switch for a second to discharge any "leftover" electricity and then open up the case. Disconnect all the drives (floppy, CDROM, DVD etc.)from the motherboard (mobo) and also disconnect your Hard Drive(s) from the mobo. Do not leave the hard drives connected, the system will boot into BIOS just fine with no hard drive attached. Unplug the power from all those drives you disconnected from the mobo and remember to disconnect the front panel firewire and/or USB ports. If you have a PS2 keybard and mouse, use them instead of the USB models.
Next, remove all the RAM, except for one stick, from the mobo. Some mobos are very picky about where the RAM needs to be placed so make sure the one stick of RAM is in the correct slot as per your manual. On the A8N SLI Deluxe this slot is the third one (B1) as you move away from the CPU.
If you're SLI then remove the second video card. Remember to set the SLI Selector Card to single. Unplug the EZ plug molex from the board.
Now you are stripped down to a barebones system. The PSU, the mobo itself, 1 stick of RAM, the CPU/HSF and one video card. Reset your CMOS/BIOS while the system is stripped down, unplugged and open. You do this by removing the battery and then moving the jumper near the battery around. On the A8N SLI Deluxe there is a set of three pins, with two covered by a jumper, right next to the battery. After removing the battery, you move the jumper from pins 1&2 to pins 2&3 and let it set for a few seconds, then reset the jumper back to pins 1&2 and replace the battery. BIOS will be back to default settings after doing this.
Now, check that everything is seated correctly, RAM, video card and its power plug if applicable and the 3 pin CPU HSF power plug. Check that both 4 pin (P4 Power)and 24 pin power is connected and secure. Now plug the PSU back into the wall and turn it on. The green LED on the mobo should be lighted. If the LED is lighted then turn the PC on. Hopefully she boots right back into BIOS.
If you get back into BIOS you can start troubleshooting by turning the PC off, unplugging it and reconnecting peripherals one at a time. The idea here is to connect and reboot, until something hangs your system up. This, presumably, is the bad piece of gear. Start with the optical drive and floppy drive, then the hard drive with the OS on it and finally the second video card if applicable.
If you cant get into BIOS then you know it is either the PSU, the RAM, the CPU, the mobo itself or the video card. Change out each of these until you get into BIOS. I would start at the PSU as it is usually the guilty party in a situation like this and is also easy to change in and out (you are down to just 2 plugs, now, remember). Next up would be the video card and/or RAM and if still no luck then things get hard as you now have to consider either the CPU or the mobo.
Good luck and happy hunting.
MERC