Gateway 500XLS Yorktown

I have an old pentium 4 Gateway computer. It is just fine for me because it is fast with 1 GB of memory, 3.066 MHz effective speed.
It very recently developed a problem with loading from the hard drive. after a few minutes operation, the hard drive clanks, whirrs & stops loading anything. When cool, the computer loads just fine. I have 2 primary hard drives: a Maxtor 40 GB and a Western Digital 40 GB that I use as primary drives and a W.D. 20 GB secondary drive. Both the primary drives function the same way -- noisy and fail to load when the computer is warm. I frequently get a message that boot has failed, no hard drive present, check cable. I have replaced cables, hard drives, added a third IDE card to operate the drives. The CD & DVD drives seem to work OK and always appear on the BIOS IDE screen. One or both of the hard drives are sometimes missing from the BIOS screen. Am I losing the IDE circuit?

Gateway 500XLS Yorktown
Windows XP PRO 2002 SP2 & 3
Pentium 4 Intel x86 Model 2 stepping
HL-DT-ST DVDRAM
LG CD-RW
WDC WD-200 PRIMARY DISK DRIVE
WDC WD-200 SECONDARY DISK DRIVE.