Clock Throttling

Looking at the performance results made me a little bit suspicious. The ASRock RX 580 is specified to run at 1380 MHz, yet the benchmarks show it to be very close to the reference RX 580, which is clocked at 1340 MHz.

So I dug a little bit deeper and monitored GPU clock over time, as listed in the chart below. Using a typical game load, not Furmark.



It's clearly visible that the card almost never reaches its clock frequency of 1380 MHz, rather running at about 1348 MHz on average (the purple line). Taking a closer look at the VBIOS and its limits reveals that the card is configured with a GPU TDP limit of 145 W, which is the default value from AMD—nearly all RX 580 cards on the market use higher values. It seems ASRock didn't touch that value for whatever reason, so I tested what power limit would be required for the card to reach its default clock all the time.



The chart above shows the GPU clock measured over three runs: one at the default power limit (purple), one with +10% (blue), and a third with +15% (red). Only the 15% curve reaches 1380 MHz all the time, it's a bit hard to see due to overlap with the blue line.

Looks like ASRock should have gone for a 165 W power limit instead—there's no doubt the card can handle it, why else would it have an 8-pin power connector rated for 225 W.

I informed ASRock about this and their feedback was that they followed the AMD TDP standard, but are considering releasing a new BIOS with a higher power limit setting.