Problem in choosing best available GPU using openCL programatically

I'm using the advice given here for choosing an optimal GPU for my algorithm. https://stackoverflow.com/a/33488953/5371117

I query the devices on my MacBook Pro using boost::compute::system::devices(); which returns me following list of devices.

Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
Intel(R) UHD Graphics 630
AMD Radeon Pro 560X Compute Engine

I want to use AMD Radeon Pro 560X Compute Engine for my purpose but when I iterate to find the device with maximum rating = CL_DEVICE_MAX_CLOCK_FREQUENCY * CL_DEVICE_MAX_COMPUTE_UNITS. I get the following results:

Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz, 
freq: 2600, compute units: 12, rating:31200

Intel(R) UHD Graphics 630, 
freq: 1150, units: 24, rating:27600

AMD Radeon Pro 560X Compute Engine, 
freq: 300, units: 16, rating:4800

AMD GPU has the lowest rating. Also I looked into the specs and it seems to me that CL_DEVICE_MAX_CLOCK_FREQUENCY isn't returning correct value.

According to AMD Chip specs https://www.amd.com/en/products/graphics/radeon-rx-560x, my AMD GPU has base frequency of 1175 MHz, not 300MHz.

According to Intel Chip specs https://en.wikichip.org/wiki/intel/uhd_graphics/630, my Intel GPU has base frequency of 300 MHz, not 1150MHz, but it does have a boost frequency of 1150MHz

std::vector<boost::compute::device> devices = boost::compute::system::devices();

std::pair<boost::compute::device, ai::int64> suitableDevice{};

for(auto& device: devices)
{
    auto rating = device.clock_frequency() * device.compute_units();
    std::cout << device.name() << ", freq: " << device.clock_frequency() << ", units: " << device.compute_units() << ", rating:" << rating << std::endl;
    if(suitableDevice.second < benchmark)
    {
        suitableDevice.first = device;
        suitableDevice.second = benchmark; 
     }
}      

Am I doing anything wrong?