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In Intel's Pentium Processor Family Developer Manual, regarding the CPU clock, it says that "it is recommended that CLK begin toggling within 150 ms after VCC reaches its proper operating level. This recommendation is to ensure long-term reliability of the device."

From a circuit implementation perspective, how might holding the clock low or high damage the device?

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    \$\begingroup\$ the manual may not be referring to physical damage, but to data integrity \$\endgroup\$
    – jsotola
    Dec 13, 2019 at 0:41

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The clock undoubtedly operates charge pumps within the chip that provide bias voltages for various functional areas. Without proper bias, leakage currents are probably higher than the transistors are really designed to handle long-term.

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  • \$\begingroup\$ I would think that would be a waste of silicon for large area caps when there are so many voltages available on MOBO's \$\endgroup\$ Dec 13, 2019 at 21:09
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If tristate bus contention can occur, the shoot thru energy temperature rise would be of the same amount of time. It seems the power on reset is not enough.

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  • \$\begingroup\$ Ah yes, maybe some part of the bus interface unit is synchronously reset \$\endgroup\$ Dec 13, 2019 at 1:06
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Not necesarily a high or low clock affects sequence but it may actually miss several clock cycles initially due to device current stabilizing thus degrading overall long term availability due to spureous error

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