Replaced cmos battery, still getting a 5 beep code.

[Redrockjdk05]

I added an upgrade ram module. After I did so my pc wouldn't boot. I get a 3 beep followed by a 2 beep code. I noticed that the ram stick I received was a 2400mhz instead of 2666mhz. I replaced the CMOS battery. It still beeps 3 times followed by 2 beeps a few seconds later. 

[TheOldMan]

The beep code is to warn of a problem.  Most likely the new memory is not compatible with the PC.

Here is the motherboard for that PC as taken from the spec page

https://support.hp.com/us-en/product/hp-slim-290-p0000-desktop-pc-series/19390524/document/c05991290

Clicking on the Memory upgrade information heading will show the memory info for memory upgrades.

First - remove the new memory to see if the PC returns to normal

Second - verify the new memory is the correct type and all parameters match.  Some motherboards are more particular about memory.  It is always good practice to match what is there exactly when adding memory.

Here is a document about beep codes

https://support.hp.com/us-en/document/c02222922

[Redrockjdk05]

I removed the new memory. It was 2400mhz module instead of 2666mhz. The original module is still in place. It did not fix the beep code. 

[TheOldMan]

The beeps are indicating a problem that needs to be corrected.  They typically are long or short beeps and the pattern is then used to see what general problem it is.

Please post a better description of the beeps indicating duration of the beeps.

Another possibility is something was disturbed while inside, changing/adding memory.

[Redrockjdk05]

Okay. When the pc is turned on the fans start running, then I get 3 consecutive long beebs then a short pause then 2 short beebs. 

[TheOldMan]

It still seems to point to the memory.  With it not actually starting, that is the assumption.  Recheck the CMOS battery is installed correctly. - you should be able to read the etching on the side facing you.

With the only original memory installed, disconnect everything not needed.  Only monitor, keyboard, mouse and power cord.

Unplug the power cord and then press and hold the power button for at least 15 seconds.  Reconnect the power cord and try a normal start.