The TDP of 35w is a maximum power consumption by the G4400T underload in associate with measurement the amount of heat dissipation by the CPU.  It does not represent the performance. 

What type of CPU stress test or load test did you perform resulting of the maximum 10w power usage. 

And what is the operating core clock in frequency (GHz) in your test.

Please note that the Intel Pentium G4400T is just an economical CPU.  It offers low energy efficiency and ideally performance, suitable for everyday multitasking.  Not a good candidate for tweaking, power enhancement, or high performance expectation.

@Chino de Oro​ I tested this CPU with 'CPU-Z' and used 'Core temp' to monitor the CPU power, it was tested at 2.9GHz, I just want the CPU to perform as it should and not be limited by power, the following conversation also It's the same issue, but he's using an i5-7500t, he seems to have switched to a 65W power supply and that solved it, but didn't explain the specifics of how the performance was playing out.https://www.dell.com/community/en/conversations/optiplex-desktops/optiplex-3050-micro-cpu-performance/647fa278f4ccf8a8de7fc830

If you ran CPU-Z, compare your CPU ranks in the benchmarks compared to other people who have used CPU-Z Validator.  As mentioned before, the Pentium CPU is a low cost processor, it can performed at 2.90 GHz max and no turbo boost mode.  If you were able to run it at 2.9 GHz then it's exceed the performing expectation.