Honestly, if stability is your top priority for 4K work and heavy rendering, I would seriously consider the Xeon route over the consumer i9. I have been building workstations for a while now, and while the Intel Core i9-14900K 24-Core Processor looks amazing for the price, those high-end consumer chips have been having some widely reported stability issues lately with power draw and heat. Plus, trying to get a stable 128GB of RAM running at high speeds on a standard Z790 board is often a total headache. I have seen so many people struggle with memory training errors when they fill all those slots... it is just not worth the stress. With a $4,000 budget, you should look into something like the Intel Xeon W5-2445 12-Core Processor. It might have fewer cores than the i9, but the platform is built for reliability. The real kicker is the support for ECC memory. If you are doing a 3D render that takes ten hours, you really do not want a single bit-flip crashing the whole thing at 95 percent. It is basically an insurance policy for your time. Quick tip: Always check the motherboard QVL specifically for 4-DIMM memory kits before buying. If you go i9, do not just buy the fastest RAM you find; stick to the validated speeds or you are definitely gonna have a bad time with 128GB stability.

Adding my two cents... for actual reliability with 128GB, focus on the platform. Consumer chipsets often struggle with high-density RAM kits. Id suggest looking at the Intel Xeon W9-3475X 36-Core Processor if you can find one within budget. Pair it with a Supermicro X13SRA-TF Motherboard to avoid those random memory-related crashes. Honestly, for professional work, ECC support is non-negotiable and worth every penny.

Late to the party but what 3D software are you actually using? Some engines love clock speeds while others just want cores... it kinda depends. If you want zero crashes with 128GB, maybe look at the Intel Xeon Gold 6426Y 16-Core Processor. It's built for heavy workloads and is way more reliable than the i9 tho. Pair it with Crucial 32GB DDR5-4800 ECC RDIMM for a super stable setup.

If youre hitting 128GB of RAM, consumer chips can get really shaky with stability, especially during long renders. For a 4k budget, id look at the Intel Xeon W7-2485X 22-Core Processor. It supports ECC memory which is a total lifesaver for 3D work. Pair it with the ASUS Pro WS W790-ACE Motherboard to handle the memory lanes properly. Itll be way more reliable than standard consumer gear.