RBE is a handy tool to modify several interesting parameters in ATI BIOS files. It focuses on fan and clock settings as these are the most important things to most users. BIOS modification is an alternative to using memory resident tweaking utilities such as RivaTuner, ATI Tray Tools or ATITool.
But RBE can do more than that: It will balance the BIOS file's checksum, lets you modify the Overdrive settings, enables superior PowerPlay functionality for some video cards, contains a CCC profile editor for hidden features of the CCC and much more.

Rx 580 Bios Hex Editor Download
Rx 580 Bios Mod
Rx 580 Bios Update
Rx 580 Bios Editor

I opened Hex editor with the modified Polaris Bios and found the location as 000f: 9c46 Len 0334 Rev 07:01 (PowerPlayInfo) So in HxD I went to Offset(h) and highlighted until the Length(h) was 334. Settings at the top were all stock as far as window width, ANSI being set and hex set.
SRBPolaris v3.5 (Download BIOS editor for AMD. Hex editing their BIOS ROM to have the same part number (113-4E353BU-O4E) as the Sapphire Pulse RX 580.

Main Features

Can display and change a lot of information strings inside the BIOS file, including Device ID and vendor ID.
Accesses every PowerPlay state and can change GPU clocks, RAM clocks and voltage for each of them seperately.
Displays the PowerPlay structure of the BIOS.
Also displays the voltages the card can make use of.
Can graphically display and modify four different fan controllers in a very comfortable way and automatically figures out which controller is used for a particular BIOS.
RBE modifies the Overdrive signature of a BIOS to enable a higher overclocking limit. Signatures can also be extracted and saved to a file.
Will make the annoying spin up bug some cards have vanish.
Enables superior PowerPlay.
Contains a profile editor for accessing hidden CCC panel features.
Acquires and flashes BIOSes all from within RBE using the built-in WinFlash interface.

Due to a digital signature requirement on latest AMD cards, RBE is no longer in active development and will not support the latest graphics cards.

Documentation

Find the official tutorial here.

RBE - Radeon BIOS Editor. RBE is a handy tool to modify several interesting parameters in ATI BIOS files. It focuses on fan and clock settings as these are the most important things to most users. BIOS modification is an alternative to using memory resident tweaking utilities such as RivaTuner, ATI Tray Tools or ATITool.

Downloads

The latest version is available in the downloads section.

Screenshots

Which video cards are supported?

So far, this might be an incomplete list:

2400
2400 LE
2400 PRO
2400 PRO AGP
2400 XT
2600 LE
2600 Pro
2600 Pro AGP
2600 XT
2600 XT AGP
2900 GT
2900 PRO
2900 XT
3200 series
3300 series
3430
3450
3470
3470 mobile
3600 series
3850
3870
3870 X2
4350
4550
4670
4770
4830
4850
4850 X2
4870
4870 X2
4890
4870 X2
HD 5450
HD 5570
HD 5670
HD 5750
HD 5770
HD 5850
HD 5870
HD 5970
HD 6850
HD 6870
FireGL V3600
FireGL V3750
FireGL V5600
FireGL V5700
FireGL V7600
FireGL V7700
FireGL V7760
FireGL V7770
FireGL V8600
FireGL V8650
FireGL V8700 Duo
FireGL V8750

All in all, the engine is somewhat flexible. If you have a video card which is not officially supported, just give it a shot nevertheless.

Revision history

v1.28

Fixed a bug that reported an error message regarding VendorID writing occasionally.
Fixed rare overdrive bug.
Added 6950 -> 6970 shader unlocking capability (will most likely only work for reference design cards).
Added 6990 DeviceID.

v1.27

Added volt modding capability for CHL8214 voltage controller (reference design 6870 and 6850 cards).
Added volt modding capability for VT1556M voltage controller (reference design 6970 and 6950 cards).
Changing DeviceID now changes both locations properly (hopefully) all the time.
Changing VendorID should work in more cases now.
Added some new DeviceIDs (6950/6970).
Updated WinFlash link.
Updated RBE's internal BIOS extraction method to account for 'ATI' labelled 'AMD' now.
Improved Hex editor interface a little.
Fixed method 1 overdrive hacking signature extraction for 6xx0 cards. Only superficially tested due to no available non-reference signatures yet

v1.26

Added (preliminary) support for Radeon HD 6850 and 6870. Everything _should_ work, except for voltage modding.
Fixed minor WinFlash version detection bug.
Improved built-in hex editor search functionality (again).
Improved flashing procedure for more stability.
Fixed Dell Subvendor-ID, thanks to Clinton for the tip!

v1.25

Added preliminary fan control for 5970 (EMC2103 fan controller). Big thanks to Diverge for making this possible!
Added support for Radeon 5830, 5450 and 5570.
Added signature file based overdrive hacking capability for 5xx0 cards. Thanks to Biker for extensive testing!
Improved built-in hex editor search capability.
Fixed another subvendor display issue, hopefully for good this time.
Improved RAM interface detection.
Fixed a rarely occurring bug (on mobile Radeon BIOSes only) regarding powerplay table.
Added qualified error message if pre-2xx0 BIOS is detected.
Fixed rare file opening issue.
Updated WinFlash link.
Fixed minor clock wizard issue.
Added welcome message for first time users.
Added feature to enable RivaTuner versions < v2.25 to cooperate with 5xx0 Radeons.

v1.24

Added 58x0 and 5970 GPU voltage control. I'd like to express my gratitude to VuurVOS who made this possible.
Added memory voltage control where available (i.e. all cards that utilize a VT1165 in order to control memory voltage, such as 4890, 5870 and 5970 [as far as I know]).
Added GPU voltage control for cards utilizing a L6788A chip. Most 4770s and 5770s use them. Hey, better late than never! :-) Unfortunately, 5670 and 5750 reference design cards can not be supported because their UP6201 chip does not support external programming.
Fixed subvendor-display on 5xx0 cards.

v1.23

Fixed 'GetStringPos' bug that occurred on rare BIOSes.
Improved RAM and RAM interface detection.
Improved 5xx0 support. Still no voltage tweaking yet.
Added 5xx0 device-IDs. These cards are featured now: 5670, 5750, 5770, 5850, 5870, 5970.

v1.22

Added clock tuning wizard.
Changed fan controller bug workaround settings' description to point out what it does a little better.
Improved program's startup routine.
Fixed 'GetClockPos reported 0'-error that came up on loading several 4xx0-BIOSes.
Added preliminary support for Radeon 5870. Note that I'm still not sure about 5850's DeviceID and that signature saving and loading will most likely not work properly on 5xx0s with this version. Furthermore, VT1165 programming is not functioning yet.

v1.21

Fixed minor glitch in BIOS flashing procedure.
Minor fixes and enhancements for hex editor.
Updated WinFlash link.
Fixed another 3650 bug.. :-/ I hate that card!
Added some DeviceIDs.
Improved specs string analysis code.
Added fan support for 4770.

v1.20

Added hex editor.
Added alternative BIOS extraction method.
(Hopefully) fixed the 3650 Device-ID-bug for good.
Fixed a bug concerning weird 4670 fan settings.

v1.19

Fixed a startup bug causing the main window not to show up.
Added experimental voltage register access. RBE automatically figures out if the card's equipped with a VT11xx. Just use register 15 for underclocking/undervolting and register 18 for overclocking. Register tweaking will over

Rx 580 Bios Hex Editor