Can the Radeon RX 7800 XT run Phi-3.5 mini Instruct?
Fits comfortably at Q4_K_M.
Phi-3.5 mini Instruct is 3.82B parameters. At Q4_K_M the weights are about 2.1 GiB; with the 1.5 GiB runtime reserve that is 3.6 GiB against the card's 16GB, leaving about 12.4 GiB for context.
All three quants
16GB card| Quant | Weights | With reserve | Verdict | Headroom |
|---|---|---|---|---|
| Q4_K_Mthe everyday quant | 2.1 GiB | 3.6 GiB | Fits comfortably | 12.4 GiB |
| Q8_0near-lossless | 3.8 GiB | 5.3 GiB | Fits comfortably | 10.7 GiB |
| FP16full weights | 7.1 GiB | 8.6 GiB | Fits comfortably | 7.4 GiB |
Verdict rules: fits comfortably when weights plus reserve sit within 85% of VRAM; tight when they fit with little left for context; CPU offload when they exceed VRAM by up to 2x (runs, slowly, with layers in system RAM); no beyond that. The KV cache per token depends on the model's architecture and is not modelled here.
The numbers for this pairing
At Q4_K_M the weights take about 2.1 GiB; with the 1.5 GiB we set aside for the runtime that is 3.6 of the card's 16 GB, leaving about 12.4 GB for the context cache.
The highest-quality version that fits entirely in memory is FP16 (full quality).
The cheapest card on our list that runs it comfortably at Q4 is the Arc B570 at about $260, against about $599 for this card.
At about $599, this card costs roughly $37 per GB of VRAM.
Running it at its full 263 W board power for 4 hours a day would use about 32 kWh a month, about $5.81 at the US average residential rate of 18.4 cents per kWh (2026-05); real use sits below that ceiling.
Prices are the lowest current listings our tracker saw on Oct 7, 2026, since averages include premium variants; launch prices are marked where we have no listing.
Good match. Get the card.
The Radeon RX 7800 XT clears Phi-3.5 mini Instruct at Q4_K_M and at Q8_0. Live listings below; this page was rebuilt 2026-10-07.
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About the model
Phi-3.5 mini Instruct by Microsoft: 131,072-token native context, text, released 2024 under the MIT. Model card →