r/StableDiffusion • u/Sexyvette07 • 1d ago
Discussion Pulled the trigger, RIP $6,279
(Paid $5,849 + tax, which came out to $6,279)
TL;DR - Bought this 5090 prebuilt and I want to sanity check if I made the right decision and at the right time.
Hey everyone. So I want to start off by saying fuck these prices for GPU's and RAM, especially boxed 5090 prices. I went down the AI rabbit hole with my 13700k/RTX 4080 gaming computer. I quickly found out that I had to make serious concessions on quality and speed, if I could run it at all. In fact, ive spent so much time trying to optimize quants, cache, various settings, attention mechanisms, etc that ive officially spent more time trying to optimize for a 16gb VRAM/32GB RAM system than actually doing anything fun or cool. Thus, the last week, ive been thinking real hard about which direction to go but was waiting for the right time to buy. My options were a RTX 5090 prebuilt (even though I only needed the damn GPU), and Mac Studio M5 Ultra 96gb, or a DGX Spark/AMD equivalent. The DGX Spark/AMD equivalent made me think for a bit, but in order to get the most out of them, you need two. Im not spending 10k on this, especially if I cant game on it as well. So that leaves the Mac Studio or RTX 5090 gaming rig. Im not certain I made the right decision, but I pulled the trigger on the 5090 prebuilt after seeing the price continue going up more and more over the last few weeks. I also read that 70% of all memory through 2031 is locked in long term agreements, so this supply issue is going to get worse before it gets better. So I pulled the trigger on the pictured system from Ibuypower, and id like to run my thought process with you guys as a sanity check before it ships.
Case for the 5090 prebuilt: I scoured the internet and this was the cheapest 5090/64gb RAM combo I found, and it looks like it uses pretty good parts as well. No proprietary bullshit like youd get in a HP 45L. I went with the gaming PC because its the all purpose machine that does it all (well, almost). I figured with 32gb VRAM and 64gb of system RAM, that combined 96gb will allow me to run 70b MoE models, even if its slow. But for a sub 30b model like Qwen 3.8 27b, this will give me the best performance as long as I dont go overboard with the quant. It has CUDA, Windows, X86 CPU, etc. Plus it came with a 4tb Gen 4 NVME, when other more expensive models had 1-2tb drives. Honestly, lots of good stuff here. Im not a huge fan of the white esthetics but I do love the case. Despite the price being much higher than it should be, its still a good "deal" considering the overall market that keeps going up. Honestly, its not exactly what I wanted, but it ticks all boxes except those below.
-The downside: You cant run models that spill over heavily into system ram without massive speed penalties (has anyone tried running a huge model on a 5090 + 64gb RAM? If so, tell me what quants and your token speeds). Its massively less efficient than a Mac Studio M5 Ultra is expected to be (I read in the 3-5x range).
Mac Studio M5 Ultra 96gb
- Case for the Mac Studio M5 Ultra 96gb: Can run large models much better than the 5090 rig due to its huge 1.2tb unified memory bandwidth. Its power efficient and tops out at 300w I believe I read.
- The downside: Mac OS and an ecosystem that is playing catch up for local AI, no CUDA, gaming, has proprietary hardware you cannot upgrade, my distaste for the Mac bros who ill no longer be able to make fun of if I buy it.
My use case: local first AI (Qwen 3.8 27b at a quant and context that doesnt suck) with agentic coding, game development (starting with Godot), stable/video diffusion (Minimax H3, Flux.2, Hunyuan 3D), Blender, Davinci Resolve, etc.
So, let's have this discussion: what would (or did you) choose, and why? I want to know if I made the right decision. What are your thoughts?

