Would you take the Costco PC or change the DIY parts list?

Based on those two exact options, I’d lean toward the prebuilt. It has the stronger CPU and GPU for gaming, and the 9800X3D is a particularly strong fit for aiming at high, steady frame rates in CS2. The custom list costs more while stepping down on both of those parts.

Before buying, check the prebuilt’s return policy and the exact power supply, memory speed, and motherboard details. The listed specs leave some of that unclear, so don’t assume every component is premium just because the headline parts are.

The 16GB versus 12GB VRAM difference is worth thinking about, but it only decides this if your actual development work needs that extra memory. Some local AI models and larger workloads can be constrained by VRAM. For regular coding and multitasking, it may not matter much.

If local AI is a serious priority, I wouldn’t treat the current DIY list as the answer automatically. I’d price a revised build that prioritizes the GPU and VRAM, and trims expensive extras like the liquid cooler or premium SSD if they aren’t needed. If CS2 is the main use, the Costco configuration looks more compelling.

That DIY list seems to spend a lot on parts that won’t help much with your stated goals. A top-end cooler and premium SSD are nice, but I’d rather put that money toward a better GPU or keep it in my pocket. Also check whether you actually need a paid Windows Pro license for your work.

I’d compare the prebuilt against a fresh DIY parts list, not just these two as written. If you value choosing every component and handling repairs yourself, building still has a real upside. It just doesn’t look like the better performance deal at these listed prices.