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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 '19 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\$ – Tony Stewart Sunnyskyguy EE75 Dec 13 '19 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\$ – Zane Kaminski Dec 13 '19 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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