Modifying A Radeon's BIOS
Aside from the R9 390, we tested each Radeon card with its original BIOS and a version of the firmware we modified ourselves to optimize GDDR5 memory timings with multiple straps, thanks to the AtiWinflash and PolarisBiosEditor utilities.
The latest version of PBE makes this easier. While it was previously necessary to manually copy the timings used on one strap to the next-higher strap, a simple button in the GUI now lets us apply better timings to each strap. This modification is mostly useless with Sapphire's RX 470 Mining, though, as the manufacturer already tuned its memory in the mining-specific BIOS.
Of course, we could always modify the firmware more extensively by adding intermediary straps or hard-coding the voltages/frequencies. For now, we're happy with our simpler adjustments, particularly since the stability of each tweak needs to be verified before considering it successful.
At this point, AMD's drivers must be patched with the ATI Pixel Clock Patcher in order to allow the graphics card to function with a modified BIOS.
How Well Does It Work?
Next, we measured the performance changes using 3DMark's Time Spy benchmark. Pleasantly, performance increases a little after our adjustments. Just remember that this is one specific case and just one sample, so there's no way to generalize about gaming performance based on these numbers. And contrary to our mining tests, we had to increase the GDDR5's voltage a little to stabilize the cards for 3D workloads.
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