Is the Dell Pro Slim Plus QBS1250 good for gaming?

Only for light or older titles. It relies on Intel integrated graphics, so demanding games will run poorly. A dedicated GPU is not a realistic option in this slim chassis.

Can I add more RAM later?

The platform supports up to 32 GB, which this configuration already has. Treat memory as fixed for the life of the machine.

How many monitors can it drive?

It has three DisplayPort outputs, so up to three displays can run from the integrated graphics. You will need DisplayPort cables or adapters for HDMI or USB-C monitors.

Is it good for video editing or CAD?

It handles light editing and 2D CAD well thanks to the 20-core CPU and fast SSD. Heavy 3D rendering and GPU-accelerated effects will be slow without a discrete graphics card.

What comes in the box?

Expect the desktop, a power cable and documentation. Keyboard, mouse and monitors are usually sold separately, so check the listing before ordering.

How does it compare with a consumer mini PC?

It is larger but easier to service, and it adds Windows 11 Pro, business manageability and three video outputs. Consumer minis are often smaller and cheaper but less expandable.