Quoteslower-than-expected graphics performance

QuoteGMK NucBox K16
AMD Ryzen 7 7735HS, Radeon 680M   
38890 MB/s

Theoretical memory bandwidth for a dual-channel system is:
102.4 GB/s = 128-bit (2*64-bit for a (SO-)DIMM desktop/laptop system; or 8 * 16-bit, or 4 * 32-bit for a LPDDR5(X) one) * 6400 MT/s / 1000 / 8.

For a single-channel the theoretical speed is: 51.2 GB/s = 64-bit * 6400 MT/s / 1000 / 8.
And the actual speed in practice lies often between 0.7 and 0.8 of the theoretical value:
35.84 GB/s = 51.2 GB/s * 0.7.
40.96 GB/s = 51.2 GB/s * 0.8.

The measured 38.890 GB/s align perfectly with the theoretical values range of 35.84 GB/s to 40.96 GB/s.

QuoteGMK NucBox K16
AMD Radeon 680M, AMD Ryzen 7 7735HS   
1518 Points

3dmark.com/search -- 680M Time Spy: "Average score: 2595"
Half the speed confirms again the single-channel configuration.

Conclusion: Looks like people who buy this -- and it's not exactly 200 bucks -- get scammed with a single-channel system. And since the memory is soldered, one can't simply add another SO-DIMM memory stick into the second channel.