I've not seen HP locked CPUs. Only Dell and Lenovo.
You can buy a 7v12 (64 core, 128 thread) with motherboard and RAM combos on eBay for $1500. Pretty cheap for the amount of computing power they have.
I just prefer to buy the ASRock motherboards instead of the Supermicro ones. The ASRock boards boot much faster than the Supermicro. Which realistically isn't a problem once the system is up and running, but I'm super impatient.
I've got:
Dual motherboard setup with 2x 64 core CPUs (ROME) and 5x P100 GPUs.
Single motherboard setup with 1 64 core CPU (ROME) and 6x P100 GPUs.
Single motherboard setup with 1 32 core CPU (ROME) and 6x 3070 GPUs.
My favorite thing about these setups is the IPMI (BMC) remote management hardware/software built into the boards that allow full control of the system remotely including access to the BIOS. All from a web page.
Future plans include replacing the 32 core CPU with a 64 core part.
Two more 64 core ROME single board setups.
One 64 core Genoa single board setup.