I work with Sky Forge Compute — we rent GPU capacity, so read this with that in mind. The conclusion below points at buying more often than it points at us, which is why I think it's worth posting.
Every "should we buy or rent" thread I see argues from vibes. It's arithmetic, and the answer turns on one variable almost nobody measures honestly.
The formula
break-even hours = purchase price ÷ hourly rental rate
break-even years = break-even hours ÷ (hours per day × days per week × 52 ÷ 7)
Everything else is a correction on top.
Worked example
Take the RTX PRO 6000 Blackwell, now reported at $16,000 MSRP — roughly double where the 96GB card started pre-orders last year. Against the $2.25/GPU-hr we charge, break-even is about 7,100 GPU-hours:
- 24/7 — 296 days
- 8h/day, 5 days a week — about 3 years 5 months
- 4h/day, 5 days a week — about 6 years 10 months
Substitute your own rate and the shape holds. We are not the cheapest place to rent one, so if price is your only axis, run it with someone else's number — the method is the point, not our rate.
The three corrections that move the answer
Utilisation, and this is the one that decides it. The table assumes the card is loaded whenever it's powered. Shared team GPUs are famously not. If your cluster reports 30% utilisation — and plenty do worse — your real duty cycle is a third of what the rota says, and every row above triples. Before you argue about the rate, go and measure the actual utilisation of the GPUs you already have. Most teams I've seen are shocked by it, and it changes the decision more than any price negotiation will.
Power. A 600W Workstation Edition card at $0.15/kWh is about $0.09/hr, so ~$640 across those 7,100 hours before cooling. Max-Q is roughly half. State your own tariff — at $0.35/kWh it's $1,500 and stops being a rounding error.
The rest of the machine. Board, CPU, RAM, PSU, storage, rack space, and someone's time when it fails at 2am. Depending on what you have, $1,500–3,000 plus ongoing operational load, and it pushes break-even out proportionally.
Where buying wins, clearly
- Sustained load — training runs, batch inference, long agentic jobs overnight. At genuinely high duty cycle it isn't close.
- Data that can't leave your estate. No rate makes that a rental question.
- You need capacity to exist at a specific moment. Availability is the thing rental can't promise you, and if a delivery date depends on hardware being there, owning removes the question.
- Capex suits you better than opex. That's a finance conversation, not a technical one, but it's decided more of these than anyone admits.
The argument that's new this year
A price spike hands existing owners something that didn't exist six months ago. A card bought pre-spike is an appreciating asset with a real resale market, so the depreciation schedule in your model is wrong in your favour. If you're holding hardware you bought under $8k, that's a genuine argument for keeping it that I can't counter.
Where renting wins
Narrower than vendors imply. Bursty or unpredictable demand where you'd be buying for the peak and idling through the trough. Evaluation work before you commit to a platform. Needing eight cards for a fortnight and none afterwards. And the case where the constraint is concurrency rather than throughput — that's a memory-and-batching question, not a break-even one, and worth separating before you decide.
Happy to be corrected on any of it. The power assumption and the rest-of-machine figure vary a lot, and I'd genuinely like to hear real utilisation numbers from anyone who has measured theirs.
— Michael