Break-even index / RTX 5090 / GPT-5.5 / New Jersey
Will a RTX 5090 build beat GPT-5.5 in New Jersey?
Your rig pays for itself in 14 months — after that you bank roughly $152/mo versus the cloud. Clear win.
How to read it: OWN — the rig pays for itself inside 18 months. HYBRID — break-even lands between 18 and 36 months; real, but slow. RENT — it never pays off before the hardware is due for replacement. Every formula and threshold is public on the methodology page.
The numbers
| Build cost (RTX 5090 build) | $3,500 ($3,000–$4,000) |
|---|---|
| Hardware amortized (3 yr) | $97.22/mo |
| Electricity in New Jersey ($0.190/kWh) | $12.83/mo (67.5 kWh) |
| Local total cost of ownership | $110/mo |
| GPT-5.5 at the same usage | $263/mo |
| Break-even | about 14 months |
Assumes the "coding assistant" preset: ~15M tokens/month, 3 h/day active, 5 h/day idle. GPT-5.5 priced at $5/M in, $30/M out (verified 2026-07-05). Rig ceiling: 70B+ with real context windows. Jargon: VRAM is the GPU memory that decides which models fit; Q4 is 4-bit quantization — a smaller, faster copy of a model with a slight quality cost.
See your verdict — then tweak every number →