Sonnet eGFX Breakaway Box 350
Expert rating6 / 10
- Connection:
- Thunderbolt 3
- PSU:
- 350W
- GPU Fit:
- Single-slot only
- Noise:
- Ultra-low-noise Noctua fan
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Manufacturer: Sonnet Last updated: 2026-09-12
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Sonnet eGFX Breakaway Box 350 (Thunderbolt 3 / 350W PSU / Single-Slot GPU / Ultra-Low-Noise Fan / Compact) Review
If you're looking specifically for a compact, quiet single-slot eGPU enclosure like the Sonnet eGFX Breakaway Box 350 rather than a full-size double-wide box,
it's built for exactly that: a smaller 350W supply, a single-slot card limit, and a Noctua fan tuned for quiet operation, which makes it the pick for lighter workloads like video editing acceleration rather than a top-end gaming GPU.
What It Actually Is
The Breakaway Box 350 is Sonnet's smallest and quietest eGFX enclosure, built with a 350W supply and a single-slot GPU limit rather than the double-wide support most of this category offers. Sonnet fitted it with an ultra-low-noise Noctua fan, and it originally shipped bundled with GPUs for Avid HDX video workflows where a quiet, compact accelerator mattered more than raw gaming power.
Comparison to Alternatives
Every other Sonnet box in this category, the 550, 650, and 750ex, supports double-wide cards and far more wattage, so the 350 only makes sense if your card is genuinely single-slot or you specifically want the quieter Noctua fan. Compared to the Sonnet eGFX Breakaway Puck's pre-installed compact GPU approach, the 350 still lets you pick your own card, just within a tighter single-slot, lower-power envelope.
Specifications
Identity
| Brand | Sonnet |
|---|
Connectivity
| Connection Standard | Thunderbolt 3 |
|---|---|
| Extra Ports | None onboard beyond the GPU's own outputs |
Power & Compatibility
| PSU Wattage | 350 W |
|---|---|
| Host Power Delivery | 15 W |
| Max GPU Length | 220 mm |
| Cooling Type | Active, ultra-low-noise Noctua fan |
| Model | eGFX Breakaway Box 350 |
|---|---|
| GPU Compatibility | Single-slot cards, GTX 1050 Ti to mid-range single-slot workstation and gaming cards |
| Price | Launched around $299 (2017) |
Expert Review
Reviewed by Burooj Alam. Rated by us, not by users.
Expert rating6 / 10
A niche but well-executed pick for single-slot cards and quiet operation, not for gaming-class GPUs.
Best for
- Video editors running single-slot acceleration cards for Avid HDX or similar workflows
- Buyers who specifically want a quieter Noctua-fan enclosure
- Compact desk setups where a full double-wide box is overkill
Not for
- Any double-wide gaming GPU, since the chassis physically won't fit one
- Buyers wanting real laptop charging power (only 15W here)
- Anyone chasing high frame rates on a modern RTX card
FAQs
What are the key specifications of the Sonnet eGFX Breakaway Box 350 (Thunderbolt 3 / 350W PSU / Single-Slot GPU / Ultra-Low-Noise Fan / Compact)?
The Sonnet eGFX Breakaway Box 350 (Thunderbolt 3 / 350W PSU / Single-Slot GPU / Ultra-Low-Noise Fan / Compact) is a eGPU enclosure from Sonnet. Key specs: Connection Standard Thunderbolt 3, PSU Wattage 350, Max GPU Length 220, Host Power Delivery 15, Extra Ports None onboard beyond the GPU's own outputs.
Who is the Sonnet eGFX Breakaway Box 350 (Thunderbolt 3 / 350W PSU / Single-Slot GPU / Ultra-Low-Noise Fan / Compact) best suited to?
It suits video editors running single-slot acceleration cards for avid hdx or similar workflows, buyers who specifically want a quieter noctua-fan enclosure, compact desk setups where a full double-wide box is overkill.
What are the drawbacks of the Sonnet eGFX Breakaway Box 350 (Thunderbolt 3 / 350W PSU / Single-Slot GPU / Ultra-Low-Noise Fan / Compact)?
It is a poor fit for any double-wide gaming gpu, since the chassis physically won't fit one, buyers wanting real laptop charging power (only 15w here), anyone chasing high frame rates on a modern rtx card.
Compare and read more
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- OWC Mercury Helios 3 (Thunderbolt 3 eGPU Enclosure / 400W PSU / Bus-Powered Charging / Predecessor to Helios FX) vs Sonnet eGFX Breakaway Box 350 (Thunderbolt 3 / 350W PSU / Single-Slot GPU / Ultra-Low-Noise Fan / Compact)
- Razer Core V2 (Thunderbolt 3 eGPU Enclosure / 500W PSU / 100W Laptop Charging / Original Full-Size GPU Box, Pre-Chroma) vs Sonnet eGFX Breakaway Box 350 (Thunderbolt 3 / 350W PSU / Single-Slot GPU / Ultra-Low-Noise Fan / Compact)