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HP Recommended

【HP ENVY 27 (TPC-P045-27) No Boot, Black Screen, Fan Spinning. Suspected CMOS/BIOS Failure, Seeking BIOS File and Technical Support.】

 

(Product Information):

 

  • Product Model: The only model number I can see on the chassis is TPC-P045-27, which I believe corresponds to the ENVY 27-p100 series. More details may be visible in the attached photo.

  • Operating System: None installed at the moment.

(Detailed Problem Description):After a long period of disuse, my All-in-One PC fails to boot. The screen remains black with no display. The power indicator LED is solid on, so I have disassembled the computer to perform diagnostics.

 

(Troubleshooting Steps Taken):

My troubleshooting process has been as follows:

  1. My initial suspicion was a BIOS error, so I performed a CMOS reset using the motherboard jumpers after disconnecting power, but the issue persisted.

  2. I then used a multimeter to check the circuitry. The resistance on the inductor for the CPU Vcore rail measured several hundred ohms without a CPU installed. After installing a CPU (the original was an Intel 6400T; I swapped it with a known-good 6100T to rule out CPU failure, but the fault remained), the resistance dropped to below 20 ohms, which seems normal.

  3. I tested brand new sticks of DDR3L RAM in different slots, but the screen still failed to display, while the fan continued to spin.

  4. I disconnected all peripherals and powered the motherboard in a minimal configuration using a bench power supply. The current draw stabilized at approximately 0.65A and would not proceed further into the boot sequence.

  5. Based on this, I began to suspect that a failed CMOS/BIOS chip was preventing initialization. I desoldered the CMOS chip and attempted to read it with a CH341a programmer on two different computers, neither of which could detect the chip.

  6. Even with the CMOS chip removed, powering on the motherboard results in the same current draw of ~0.65A.

  7. Therefore, my current diagnosis is a failed CMOS chip, which is causing the power-on sequence to halt before the BIOS can be read. I have ruled out the CPU and RAM as the cause of the issue through cross-testing with minimal components.

 

(Desired Assistance):

I am looking for the following assistance:

  1. I would like to obtain the BIOS.BIN file for this specific motherboard so I can flash it onto a new replacement Winbond chip.

  2. I am looking for a functional replacement CMOS chip for this model, or alternatively, a non-functional donor motherboard from which I could salvage the part. I am willing to cover any postage costs.

  3. I welcome any additional expert advice or discussion with fellow enthusiasts who may have encountered a similar issue.

 

IMG_20250708_200847.jpgIMG_20250708_200919.jpgIMG_20250708_201248.jpgIMG_20250709_000656.jpgIMG_20250709_075658.jpgIMG_20250709_071425.jpgIMG_20250708_200851.jpg

 

1 REPLY 1
HP Recommended

@Richard_Young,

 

Welcome to our HP Community forum!

 

1.) HP ENVY 27-p100 All-in-One Desktop PC series (Touch) Software and Driver Downloads | HP® Support.

 

2.) You can purchase a "parts only" motherboard via eBay, but it would be anyone's guess if you actually bought one with a functional CMOS chip.  A working motherboard is inexpensive enough, such as this purchase option for under $33: HP ENVY 24-N 27-P INTEL CHIPSET H170 SOCKET LGA1151 AIO MOTHERBOARD 797425-001 | eBay.

 

3.) In my experience, messing around with chips and capacitors and such often leads to frustration and sucking up time & efforts: replace your motherboard would be my recommendation.

 

Kind Regards,

 

NonSequitur777


† The opinions expressed above are the personal opinions of the authors, not of HP. By using this site, you accept the <a href="https://www8.hp.com/us/en/terms-of-use.html" class="udrlinesmall">Terms of Use</a> and <a href="/t5/custom/page/page-id/hp.rulespage" class="udrlinesmall"> Rules of Participation</a>.