My pc shows no signal and pc turns on

Hi @mosenicholson

As best as I can find out based on the serial number that you posted, the desktop is a HP Compaq Pro 6380 Base Model Microtower PC.

Are you sure that it is turning on and booting into the OS and not just starting and failing to pass POST (power on self test), therefore not booting into the OS? Starting and booting are two different actions. Sequence is, PC is turned on, it performs POST and if all the hardware is OK then it boots the OS into loading the operating system

With HP desktops mostly a single beep on startup indicates a power problem or sometime a ram problem if it is a long beep.

Try the following and check if any of them work to get the desktop starting, passing POST and booting with a display or even getting into BIOS on startup with a display.

i. Perform a power refresh.

Turn off the PC if it is on and then disconnect the power cord from the PSU. Press and hold the PC Power On button for 20 seconds and then release it. Reconnect the power to the PSU and check if it turns on.

ii. If still no good, try a full power refresh.

Turn off the PC if it is on and then disconnect the power cord from the PSU. Open the PC case and locate the coin cell RTC battery on the motherboard and remove it from its holder. When it is out measure its voltage. If it is <2.5V DC, replace it. The battery model number should be printed on the battery itself. Usually they're a CR2032 Lithium coin cell, available most everywhere.

Press and hold the PC Power On button for 20 seconds and then release it.

Reinsert the RTC coin cell battery (or its replacement, into its holder on the motherboard (+ve side up as marked on the battery), reassemble the desktop, reconnect the power to the PSU. Reconnect the power to the PSU and check if it turns on.

If it does turn on with a display, there may be a message stating that the date and time are incorrect. This is normal as the BIOS has been reset back to its factory default setting. Once the date and time have been corrected the message won't appear again the next time the PC is started.

iii. If still no good, looking at the specifications and images of the PC's PSU it seems like it is an ATX type PSU and not a proprietary HP PSU. If this is correct use a DMM (digital multimeter) to check if all the voltages being supplied by the PSU are correct by performing a paperclip test on the PSU.

If still no good and if you can't even get into BIOS with a display, then there's a motherboard problem.