Does the case support full-sized graphics cards, and what is the maximum GPU length it can accommodate?

The case can accommodate graphics cards with a maximum length of 310mm.

What are the dimensions of the C26 Yellow Portable MINI Computer Case, and will it fit into a standard desktop setup?

The dimensions of the C26 Yellow Portable MINI Computer Case are 315MM x 155MM x 265MM.

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C26 Yellow Portable MINI Computer Case (Support MATX/ITX Motherboard/A4 Aluminum/Side-Opening Glass Side Through) Type-C + USB3.0

Size: 315MM*155MM*265MM
Motherboard support type: ITX/MATX
CPU heat sink support height: within 130MM, graphics card support length: within 310MM
Power support: SFX/SFX-L(SFX Better)
Weight: Gross weight: 8.62KG