I think P5K BIOS chip is soldered so hot swapping is out of the question.
There is bootstrap inside ASUS BIOS chip that never gets flashed and should not be corrupted: you put USB stick with original BIOS, press combination of keys and it should do emergency BIOS flash on non working computer. Don't remember key combination, it should be in the manual or ASUS board. I had similar thing with Asus P5b-e, computer went dead due to POS BIOS update ASUS posted on it's website. Nothing would work until I got very old PCI (not PCIexpress but standard PCI) video card, that got me to BIOS screen and let me load older BIOS back, you could try that as well (remove PCIe card before restarting). I don't know what is it about Asus or other mobo makers, you would think by now they would have something as simple as BIOS flash down to the science. Hope you get it running.
Those are instructions for Asus crash free BIOS for P5B-e, I have no idea if P5K is the same and I don't even know if they work since old PCI video card trick worked for me but with dead computer you have nothing to loose, I think.
1&2 download and copy original version of BIOS to USB or floppy
3. Now put that floppy disk in your PC that has POST problem (if you have no floppy drive, try USB flash disk)
4. Now you need to gain access to ASUS CrashFree BIOS 3 utility. It is not easy, but here what I did. Restart PC by pressing restart bottom on your PC case and immediately press those keys on your keyboard at the same time CTRL+ALT+ DEL+PAGE DOWN . Now, last to keys DEL & PAGE DOWN you have to press. Do not press keys that located just above four arrows on your keyboard, but press the same key but those that located to your far right in the end of your keyboard. As your PC will boot try pressing and releasing and pressing again those keys or just pressing them and just holding them. Try both methods. If you do exactly as I said you will here multiple beeps, that means you entered ASUS CrashFree BIOS 3 utility successfully. This is most important step, to enter CrashFree BIOS 3.
5. This utility will search your CD-ROM drive, floppy drive, USB drive. On your floppy drive it will find floppy disk that you placed before with P5BE.ROM file. It will say " Reading file P5BE.ROM. Completed".
6. Now, ATTENTION!!!. When utility will say Start flashing...(or Start erasing). Let it finish this task. Then it will say Start programming.... Now you have to shut down your PC Immediately !!! Do it by pressing shut down bottom on your PC and hold it for 5 seconds or by taking out plug from the back of the PC. Do not let the utility to finish programming task!
7. Now when your PC is shut down wait for 5 min.
8. Remove your floppy disk from floppy drive.
9. Then put in your CD-ROM drive, ASUS support CD that came with your motherboard.
10. Start your PC. And again in order for you to access ASUS CrashFree BIOS 3 utility, repeat steps that I described in step number 4. Hold down those keys or stroke them again and again during boot up process. If you need restart your PC by pressing restart bottom and try again until you successful.
11. When you enter CrashFree BIOS 3 again, utility will do what it did last time. Only this time it will not find floppy disk, but will find ASUS support CD in your CD-ROM drive.
12. This time don't do anything until whole process is complete. First, it will say again "Reading file P5BE.ROM. Completed". Then "Start flashing...(or Start erasing)". Then "Programming...\\) Wait until it will say flashing process is complete and you have to shut down your PC. Now, do not restart PC, shut it down completely, as I wrote in step number 7.
13. Wait for 5 to 7 minutes, then power up your PC.
14. PC will boot, but it will stop with message about your memory voltage incorrect or failed overclocking. Just press F2 to load BIOS defaults for now.
15. Your PC should boot normally and load Windows.