Hello I'm looking to upgrade my HP Pavilion gaming desktop

[Jason852]

I have the hp8643 motherboard I was wondering if I could replace the Ryzen 5 3500 CPU which came with the PC for an i9900k CPU 

[itsmyname]

Is this your computer: HP Desktop PCs - motherboard specifications, Erica | HP® Customer Support

That document lists various "upgrade" processors, and the socket-type for the processor, which determines which processors fit into that socket. 

You may need a BIOS update to support a non-standard processor.

[Prométhée]

Hello
sorry, but if you have an HP motherboard, with Socket AMD, you cannot install an intel processor, update or not bios, it is physically impossible

[itsmyname]

> replace the Ryzen 5 3500 CPU

Is this your current processor: AMD RYZEN 5 3500X 6-Core 3.6 GHz (4.1 GHz Turbo) Socket AM4 65W 100-100000158CBX Desktop Processor

It has 6 cores, but does not support hyperthreading, unlike the RYZEN 5 3600, which has a total of 12 threads, each at 3.6 Ghz.  Reference: https://www.newegg.ca/amd-ryzen-5-3600/p/N82E16819113569

So, what programs do you run that will actually use the 7th through 12th threads?

From: https://www.newegg.ca/amd-ryzen-5-5600x/p/N82E16819113666

there is: AMD Ryzen 5 5600X Vermeer 6-Core 3.7 GHz Socket AM4 65W 100-100000065BOX Desktop Processor

Only slightly faster, but the same 65W requirement, and the same socket. Price is: $329.99 plus taxes

That's a lot of money for only a slight speed-up of each core.

[Prométhée]

🤔

https://support.hp.com/us-en/document/c06418627

Processor upgrade information

• TDP: up to 65 W
• Socket type: AM4
• Motherboard supports the following processor upgrades:

  Processor	TDP	Integrated graphics
  AMD Ryzen 5 3400G, 3.7 GHz Base frequency, up to 4.2 GHz burst frequency, 4 MB cache, Quad core (Picasso)	65 W	Radeon Vega 11 Graphics
  AMD Ryzen 3 3200G, 3.6 GHz Base frequency, up to 4.0 GHz burst frequency, 4 MB cache, Quad core (Picasso)	65 W	Radeon Vega 8 Graphics
  AMD Athlon 300UGE, 3.6 GHz Base frequency, 4 MB cache, Dual core (Picasso)	65 W	Radeon Vega 3 Graphics
  AMD Ryzen 5 3500, 3.4 GHz Base frequency, up to 4.1 GHz burst frequency, 16 MB cache, Hexa core (Matisse)	65 W	NA
  AMD Ryzen 7 3700X, 3.6 GHz Base frequency, up to 4.4 GHz burst frequency, 32 MB cache, Octa core (Matisse)	65 W	NA

[Jonathon33]

But could you use a 5000 series cpu and it work? More interested in it because I want to use SAM.

[Prométhée]

Using a processor, not validated, which is not indicated in the product sheet, will work in rare cases!
If you spend a few series of processors, even less luck
it's up to you, you can try

I saw a case, but with intel, the user successfully installed an invalid processor, but a bit of luck anyway