Try reduce_sum but seems unsuccessfully enabled multicore computation

[AlchemistXC]

I tried to use cmdstanR on two computers to apply multi-core parallel computing, however, the CPU utilization seems to be not as good as expected.
The configuration of the first computer is：
CPU：12th generation Core i7-12700（12 cores and 20 threads）
RAM：32g
System： Win11
The CPU utilization monitored by the system is：

The code used：

model3_1 = cmdstan_model("lee-carter3_1reduce_sum.stan",cpp_options = list(stan_threads = TRUE),stanc_options = list("O1"))
  lc_fit2010_3_1 <- model3_1$sample(standata3,
                                chains = 4,
                                parallel_chains = 4,
                                iter_warmup = 1000,
                                iter_sampling = 1000,
                                # max_treedepth = 15,
                                # adapt_delta = 0.95,
                                threads_per_chain = 5,
                                refresh = 1)

The configuration of the second computer is：
CPU：Dual Xeon Platinum 8172M（52 cores and 104 threads）
RAM：191g
System： Win10
The CPU utilization monitored by the system is：

There seem to be only a few cores at work.
The code used：

model3_1 = cmdstan_model("lee-carter3_1reduce_sum.stan",cpp_options = list(stan_threads = TRUE),stanc_options = list("O1"))
  lc_fit2010_3_1 <- model3_1$sample(standata3,
                                chains = 4,
                                parallel_chains = 4,
                                iter_warmup = 1000,
                                iter_sampling = 1000,
                                # max_treedepth = 15,
                                # adapt_delta = 0.95,
                                threads_per_chain = 26,
                                refresh = 1)

Is this CPU utilization normal, or am I making a mistake in the settings?

[AlchemistXC]

Supplementary: the system processes are monitored as follows (the first line is the system idle process, the next 4 lines are the processes of stan)
The first computer：

The second computer：