Does the Intel NUC 13 2023 come with any pre-installed operating system?

No, the Intel NUC 13 2023 does not come with any pre-installed operating system.

What is the maximum clock speed of the Intel Core i5-1340P in this mini PC?

The Intel Core i5-1340P can reach a maximum clock speed of up to 4.6GHz.

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Intel NUC 13 2023 NUC13ANKi5 Barebone System Slim Mini PC Desktop i5-1340P up to 4.6GHz, No RAM, No Storage, WiFi 6, Bluetooth 5.3, No OS

Intel NUC 13 Pro NUC13ANHi5 Mini PCs, Kits, and Boards offer the perfect combination of size, performance, sustainability, and reliability to drive modern business. It starts with 13th Gen Intel Core i5-1340P, 12C (4P + 8E) / 16T, P-core up to 4.6GHz, E-core up to 3.4GHz, 12MB
Intel Iris Xe Graphics. Connect up to four 4K extended displays.
Memory: None; Storage: None.
Networking: Intel Wi-Fi 6E (Gig+), Bluetooth 5.3;