I have rx580's and i am only getting 21Mhs on windows 10 with compute mode, latest amd drivers, latest windows updates, Phoenixminer 5.4c.
i have tweaked the gpu's in AMD control panel cvddc 853 cclock 1165 mvddc 853 mclock 2080
could you please share your settings.
thanks

-cclock 1250
-mclock 2250
-cvddc 925
-mvddc 825

PolarisBiosEditor1.7.4 allows you to modify a bios file and save it and then use
atiflash_293 to flash your bios.

Make sure you save the original bios before flashing the new one in case you need to revert.

This version the gui would not work for me on windows so i used the command line to run the flashing and saving.

C:\atiflash_293>amdvbflash.exe /h
--- amdvbflash v2.93 ---
-h, -?, /h, /?          Help (this screen)

Format: amdvbflash [command] [parameter1] [parameter2] [parameter3] <option/s>
[command]:
-i [Num]                Display information of AMD adapters in the system.
                        Display information of adapter [Num] if specified.
-ai [Num]               Display advanced information of AMD adapters on system.
                        Display advanced information of adapter [Num]
                        if specified.
-biosfileinfo <File>    Displays the Bios info in file <file>
-p <Num> <File>         Write BIOS image in file <File> to flash ROM in Adapter
                        <Num>.
-pa [-padevid=] <File>  Write BIOS image <File> to all appropriate adapters.
                        Use with -padevid or -passid or -pasvid or -pavbpn or -fp.
                        Command example:
                        command = -pa -padevid=0xXXXX a123.bin
-s <Num> <File> [Size]  Save BIOS image from adapter <Num> to file <File>.
                        First [Size] kbytes (except for Theater in bytes) of ROM
                        content is saved if [Size] is specified.
-cf <File> [Sum]        Calculate 16-bit checksum for file <File>.
                        Checksum for the file is compared to [Sum] which is
                        the expected checksum
-cb <Num> [Sum]         Calculate 16-bit BIOS image checksum for adapter <Num>.
                        Checksum for the BIOS image is compared to [Sum] which is
                        the expected checksum
press any key to continue

-cr <Num> [Size] [Sum]  Calculate 16-bit ROM checksum for adapter <Num> and
                        compare it to the [Sum] specified.  This command is
                        the same as -cb if [Size] is specified.
-t <Num>                Test ROM access of adapter <Num>
-v <Num> <File>         Compare ROM content of adapter <Num> to <File>
-mi <Num> [ID]          Modify SSID & SVID in BIOS image of adapter <Num> to
                        <ID>.  SSID & SVID in BIOS image of adapter <Num> is
                        displayed if [ID] is not specified.
-mb <Num> <File>        Modify SSID, SVID, BIOS Pin Number, & Boot Message in
                        BIOS image of adapter <Num> to values in <filename>.
                        Input file example:
                           ssid = 715B
                           svid = 1002
                           biospn = "113-xxxxxx-xx"
                           bootmsg = "AMD graphic board"
-pak <File>             Package an executable for BIOS update according to
                        the commands in <File>.
                        Config file example:
                           outfile = update.exe
                           banner = "Update v1.0"
                           infile = a123.bin
                           command = -pa -padevid=715B infile
-isr <Num> <Build Number> <Board Number>  Set ISR number based on the given
                                          build and board number
                                          if not specified, print out ISR Number
-prod <Num> <12 digit serial number>      Set PROD number based
                                          on the given serial number
                                          if not specified, print out SN Number
-checkprodsn <Num> <12 Digit Serial Number>  Comparing the Prod SN based on
                                             existing prod sn saved in ROM

press any key to continue

<option/s>:
-f              Force flashing regardless of security checkings (e.g. AsicID &
                BIOS file info check OR boot-up card).
-fa             Force flashing bypassing already-programmed check.
-fm             Force flashing bypassing BIOS memory config check.
-fs             Force flashing bypassing BIOS SSID check.
-fp             Force flashing bypassing BIOS P/N check.
-sst            Use SST25VFxxx flashing algorithm regardless of ROMID straps.
-st             Use ST M25Pxx flashing algorithm regardless of ROMID straps.
-atmel          Use AT25Fxxx flashing algorithm regardless of ROMID straps.
-keepisrsn      keep the ISR Number on the adapter when flashing a new VBIOS
-keepprodsn     keep the Prod SN on the adapter when flashing a new VBIOS

press any key to continue

-siireset       Specifies the GPIO Pin to be used as the Reset when updating
                SiI1930 microcontroller firmware
                Input example:
                   -siireset=7 <No Spaces>
-siiuprog       Specifies the GPIO Pin to be used as the uprog when updating
                SiI1930 microcontroller firmware
                Input example:
                   -siiuprog=14 <No Spaces>
-scansii        Overrides normal adapter detection to enable detecting SSI
                roms with/without TPI firmware
-log            Logs output to amdvbflash.log, overrides existing file
-logappend      Logs and appends output to amdvbflash.log
-ddc            Enable DDC support
-padevid=<ID>   Use with -pa command to update adapters of specific device ID.
-passid=<ID>    Use with -pa command to update adapters of specific SSID.
-pasvid=<ID>    Use with -pa command to update adapters of specific SVID.
-pavbpn=<VBPN>  Use with -pa command to update adapters of specific VBIOS PN.
press any key to continue

-excl_memtrain_dtable     When flashing on new VBIOS, a pre-determined memory
                           training data table in the old VBIOS will not be
                          overwritten.
-isr <adapter num> [build num] [board num]     If build number and board number
                                               are specified, sets the ISR Number
                                               value in specified adapter.
                                               If only adapter is specified, the current
                                               ISR Number is displayed
-checkpn <adapter num> <filename>              Checks PN of the current product
                                               and compares it to external file
-rsa <filename>                                Verify VBIOS immage file RSA signature
*<Num> = adapter number, <File> = filename
*[Size] = data block size in KBytes, except for Theater Pro in Bytes
*Use command -i to see the adapter numbers in the system.

Hi, you don't seem to have the Modified Bios on your cards, maybe that's what you need. If you already have it modified, you can try to reinstall it and do the tests