In the theory, the Pegatron 2A86 and IPMTB-TK (Truckee) are the same exact board. IPMTB-TK should be printed on the motherboard, as depicted below;
And "2A86" will be returned by software identification means. Please try installing IPMTB-TK Motherboard BIOS Update v6.10 from the HP Pavilion Elite HPE-490t CTO Desktop PC Drivers page for your computer.
Also, this motherboard is subject to various failures and was part of a 1 year Limited Warranty Service Enhancement Program (LWSEP) several years ago. Please search the HP Forum for posts concerning the reported issue.
If you have any further questions, please don't hesitate to ask.
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