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Overclocking RT-AC56U

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If CFE 1.0.2.9 has been working for your overclock in an earlier version of Merlin firmware, then it's weird that by upgrading to 378.56, it stops working...

Otherwise, I would suggest you going back to CFE 1.0.2.6 or 1.0.2.7 _unless_ your AC56U came pre-installed with 1.0.2.9.

BTW, the latest guide for overclocking in 378.56 here:

https://github.com/kvic-z/goodies-asuswrt/wiki/Overclock-Asuswrt-Merlin-on-v378.56-and-beyond
I was able to over clock to 1200,666 using these instructions...
Overclocking on Asuswrt-Merlin 378.56_2 (RT-AC68U and RT-N66U)
 
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Im on the 1.0.2.3 CFE with 378.65_2 Merlin. I guess Im out of luck for the moment?
Any thoughts on why my 'stock' router runs at 82/83c (other than im really taxing it)? Should I set up a fan for it?
 
Recent firmware i.e. 378.55 (I haven't checked other versions) provides a new memory clock at 775MHz. A new step between 667MHz and 800MHz.

AC56U owners better stay at 666MHz if you cannot go 800Mhz. 775 slows down performance a bit. I notice that under intensive read/write in wireless throughput tests.

If someone could write a little program to benchmark and confirm that or analyse from spec sheet, that'll be great :)

(NB: 667 will reset back to 533 since some firmware versions ago)
 
fDIq9ET.jpg

I'm waiting for spare parts to my Dremel so the hole is a work in progress.
60mm hole saw and a 60mm hole.
p9mib.jpg


Drill press, clamp, and piece of 2x4 wood underneath. Speed 950 RPM or greater.
nvp854.jpg
 
So I was trying to OC for the first time:

CFE 1.0.1.9 latest merlin
tried nvram set clkfreq=1000,666
and after reboot shows default value:
nvram get clkfreq 800,533

but BogoMIPS : 1998.84 value has changed from 1600 or something similar don't remember exactly, so this confirms that it OC?
 
For AC56U, try 666 (or 775). 800 doesn't work for some batches..

To "unbrick", hold the WPS button (don't release), then power on the router. Continue to hold the WPS button for 10s. Then release the WPS button. Wait for three minutes. Everything will be back to factory default.
 
For AC56U, try 666 (or 775). 800 doesn't work for some batches..

To "unbrick", hold the WPS button (don't release), then power on the router. Continue to hold the WPS button for 10s. Then release the WPS button. Wait for three minutes. Everything will be back to factory default.

Doesn't work whit WPS button, I have serial cable so no problem it has been 3rd time when I brick some kind of router previous two was tplink.
And it's alive again :)

EDIT: you were right it boots whit 1200:775
EDIT 2:
jO4wpl7.png
finally, now need to test stability, hardest part was to tear off ac56u :D and finally I known that rev is 1.60
 
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Another success story here. I'm safely running 1000,666 without additional cooling on my AC56U. I can manage 42.5/7.5 on a 50/10 VDSL connection with a PIA VPN tunnel client on the router. I will likely add a fan so I can push it to 1200 for max VPN speed. Temp is 72C.

My temp at stock speed was 69C. I was actually able to get 34/7.5 at stock speed which seems higher than what others have reported, and that's with AES-128.

I keep the router in a closet with my DIY media server, so I'll probably just get whatever USB fan I can find and not worry about the noise.

EDIT: now that it's summer, the router is running too warm and throttles to a very slow speed which is solved with a reboot. I just took apart an old external drive enclosure and stuck the fan under the router. Temps went from 80 back down to 73 and seems to be okay now. I'll probably do something more elaborate if this isn't stable enough.
 
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Guys, my problem began when I changed something in overlock section of DD-WRT admin panel.
I think it was CPU frequency.
My ASUS RT-AC56U became a brick being stuck in a boot loop.
Code:
Decompressing...done
Detect CPU turbo button...

CFE version 6.30.163.2002 (r382208) based on BBP 1.0.37 for BCM947XX (32bit,SP,)
Build Date: 四  4月 18 09:25:12 CST 2013 (yau@wireless-pub2)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
DDR Clock: 333 MHz
Warning: invalid DDR setting of 0 MHz ignored. DDR frequency will be set to 333 MHz.
CPU type 0x0: 600MHz
Tot mem: 262144 KBytes

CFE mem:    0x00F00000 - 0x01192F4C (2699084)
Data:       0x00F4B644 - 0x00F4BA8C (1096)
BSS:        0x00F4BA98 - 0x00F90F4C (283828)
Heap:       0x00F90F4C - 0x01190F4C (2097152)
Stack:      0x01190F4C - 0x01192F4C (8192)
Text:       0x00F00000 - 0x00F42394 (271252)

Null Rescue Flag.
boot the image...
go load
Loader:raw Filesys:tftp Dev:(null) File:: Options:(null)
Loading: TFTP Server.
Failed.
Could not load :: Error
Loader:raw Filesys:raw Dev:nflash0.os File: Options:(null)
Loading: .... 4179552 bytes read
Entry at 0x00008000
Starting program at 0x00008000
console [ttyS0] enabled, bootconsole disabled
serial8250.0: ttyS1 at MMIO 0x18000400 (irq = 117) is a 16550
brd: module loaded
loop: module loaded
pflash: found no supported devices
bcmsflash: found no supported devices
Boot partition size = 524288(0x80000)
lookup_nflash_rootfs_offset: offset = 0x200000
nflash: squash filesystem with lzma found at block 29
Creating 4 MTD partitions on "nflash":
0x000000000000-0x000000080000 : "boot"
0x000000080000-0x000000200000 : "nvram"
0x000000200000-0x000004000000 : "linux"
0x0000003ab3f4-0x000004000000 : "rootfs"
PPP generic driver version 2.4.2
PPP MPPE Compression module registered
NET: Registered protocol family 24
PPTP driver version 0.8.5
=== PPTP init ===
u32 classifier
    Actions configured
Netfilter messages via NETLINK v0.30.
nf_conntrack version 0.5.0 (3990 buckets, 15960 max)
xt_time: kernel timezone is -0000
ip_tables: (C) 2000-2006 Netfilter Core Team
TCP cubic registered
NET: Registered protocol family 10
ip6_tables: (C) 2000-2006 Netfilter Core Team
NET: Registered protocol family 17
L2TP core driver, V2.0
PPPoL2TP kernel driver, V2.0
802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com>
All bugs added by David S. Miller <davem@redhat.com>
Registering the dns_resolver key type
Restarting system.

Decompressing...done
Detect CPU turbo button...

CFE version 6.30.163.2002 (r382208) based on BBP 1.0.37 for BCM947XX (32bit,SP,)
Build Date: 四  4月 18 09:25:12 CST 2013 (yau@wireless-pub2)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
DDR Clock: 333 MHz
Warning: invalid DDR setting of 0 MHz ignored. DDR frequency will be set to 333 MHz.
CPU type 0x0: 600MHz
Tot mem: 262144 KBytes

CFE mem:    0x00F00000 - 0x01192F4C (2699084)
Data:       0x00F4B644 - 0x00F4BA8C (1096)
BSS:        0x00F4BA98 - 0x00F90F4C (283828)
Heap:       0x00F90F4C - 0x01190F4C (2097152)
Stack:      0x01190F4C - 0x01192F4C (8192)
Text:       0x00F00000 - 0x00F42394 (271252)

Null Rescue Flag.
boot the image...
go load
Loader:raw Filesys:tftp Dev:(null) File:: Options:(null)
Loading: TFTP Server.
Failed.
Could not load :: Error
Loader:raw Filesys:raw Dev:nflash0.os File: Options:(null)
Loading: .... 4179552 bytes read
Entry at 0x00008000
Starting program at 0x00008000
console [ttyS0] enabled, bootconsole disabled
serial8250.0: ttyS1 at MMIO 0x18000400 (irq = 117) is a 16550
brd: module loaded
loop: module loaded
pflash: found no supported devices
bcmsflash: found no supported devices
Boot partition size = 524288(0x80000)
lookup_nflash_rootfs_offset: offset = 0x200000
nflash: squash filesystem with lzma found at block 29
Creating 4 MTD partitions on "nflash":
0x000000000000-0x000000080000 : "boot"
0x000000080000-0x000000200000 : "nvram"
0x000000200000-0x000004000000 : "linux"
0x0000003ab3f4-0x000004000000 : "rootfs"
PPP generic driver version 2.4.2
PPP MPPE Compression module registered
NET: Registered protocol family 24
PPTP driver version 0.8.5
=== PPTP init ===
u32 classifier
    Actions configured
Netfilter messages via NETLINK v0.30.
nf_conntrack version 0.5.0 (3990 buckets, 15960 max)
xt_time: kernel timezone is -0000
ip_tables: (C) 2000-2006 Netfilter Core Team
TCP cubic registered
NET: Registered protocol family 10
ip6_tables: (C) 2000-2006 Netfilter Core Team
NET: Registered protocol family 17
L2TP core driver, V2.0
PPPoL2TP kernel driver, V2.0
802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com>
All bugs added by David S. Miller <davem@redhat.com>
Registering the dns_resolver key type
Restarting system.

Then I tried to restore it with ASUS restore utility.
Didn't help.

Then I tried to connect to it with a TTL adapter and typed this:
Code:
nvram erase && nvram commit && reboot
Code:
Decompressing...done
Detect CPU turbo button...

CFE version 6.30.163.2002 (r382208) based on BBP 1.0.37 for BCM947XX (32bit,SP,)
Build Date: 四  4月 18 09:25:12 CST 2013 (yau@wireless-pub2)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
DDR Clock: 333 MHz
Warning: invalid DDR setting of 0 MHz ignored. DDR frequency will be set to 333 MHz.
CPU type 0x0: 600MHz
Tot mem: 262144 KBytes

CFE mem:    0x00F00000 - 0x01192F4C (2699084)
Data:       0x00F4B644 - 0x00F4BA8C (1096)
BSS:        0x00F4BA98 - 0x00F90F4C (283828)
Heap:       0x00F90F4C - 0x01190F4C (2097152)
Stack:      0x01190F4C - 0x01192F4C (8192)
Text:       0x00F00000 - 0x00F42394 (271252)

Startup canceled
CFE> ^C
CFE> nvram erase && nvram commit && reboot
Didn't help.
I tried to change the frequency:
Code:
nvram set clkfreq=800,533
nvram commit && reboot
Code:
Decompressing...done
Detect CPU turbo button...

CFE version 6.30.163.2002 (r382208) based on BBP 1.0.37 for BCM947XX (32bit,SP,)
Build Date: 四  4月 18 09:25:12 CST 2013 (yau@wireless-pub2)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
DDR Clock: 333 MHz
Warning: invalid DDR setting of 0 MHz ignored. DDR frequency will be set to 333 MHz.
CPU type 0x0: 600MHz
Tot mem: 262144 KBytes

CFE mem:    0x00F00000 - 0x01192F4C (2699084)
Data:       0x00F4B644 - 0x00F4BA8C (1096)
BSS:        0x00F4BA98 - 0x00F90F4C (283828)
Heap:       0x00F90F4C - 0x01190F4C (2097152)
Stack:      0x01190F4C - 0x01192F4C (8192)
Text:       0x00F00000 - 0x00F42394 (271252)

Startup canceled
CFE> ^C
CFE> nvram set clkfreq=800,533
*** command status = 0
CFE> nvram commit && reboot
Decompressing...done
Detect CPU turbo button...

CFE version 6.30.163.2002 (r382208) based on BBP 1.0.37 for BCM947XX (32bit,SP,)
Build Date: 四  4月 18 09:25:12 CST 2013 (yau@wireless-pub2)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
DDR Clock: 333 MHz
Warning: invalid DDR setting of 0 MHz ignored. DDR frequency will be set to 333 MHz.
CPU type 0x0: 600MHz
Tot mem: 262144 KBytes

CFE mem:    0x00F00000 - 0x01192F4C (2699084)
Data:       0x00F4B644 - 0x00F4BA8C (1096)
BSS:        0x00F4BA98 - 0x00F90F4C (283828)
Heap:       0x00F90F4C - 0x01190F4C (2097152)
Stack:      0x01190F4C - 0x01192F4C (8192)
Text:       0x00F00000 - 0x00F42394 (271252)

Startup canceled
CFE>
Still the same boot loop.
What can I do now? =(

WPS and reset buttons don't respond.

This router is a present from my deceased brother. Can't through it away.
 
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Try rebooting immediately after the nvram erase, do not nvram commit.
 
You are not the first one and for sure not the latest person reproducing that problem using DD-WRT FW on ASUS routers, you should try DD-WRT forum instead, they know better the reason why and probably how to fix it, I presume there's no CFE changes using DD-WRT FW, but not really sure about it.

Your 4x LAN are not working after right? Check NVRAM MAC values, I remember that was one of the problems when DD-WRT goofed it.
 
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Hello Everyone,

I am new here. I found this site while searching for information on the router that I just bought. It is the ASUS RT-AC56R. I flashed it with dd-wrt and setup my VPN (PIA) and discovered the connection speed plummeted from 118Mbs to around 25Mb on the PC and from 65Mbs to 4 MBs on the Android TV Box. I had expected a drop but that is ridiculous. While searching for solutions as to the reasons this is happening brought me to this thread. Since I was going to flash the firmware anyway I purchased a refurbished router, so voiding the warranty isn't a major concern. I would like to know if the overclocking procedures I have read about in this thread will work on the "R" flavor of the router. Apparently there are 3 flavors, "U", "R", and "S". I am not sure what the exact differences are between the "U" and the "R", I only know that the "S" has 128 MBs of RAM instead of 256 MBs. As far as I can tell, the "R" and the "U" have the same CPU's. I want to find a solution to getting the VPN back to a respectable speed. If a firmware different from the dd-wrt will work better, please tell me. I am OK will experimenting, I just don't want to spin my wheels going off in the wrong direction. Thank you for your time.
>>>>>>>>>>>>>>
Upon discovering my lack of foresight regarding this router's ability to handle the encryption computations for OpenVPN, I am now considering getting the Linksys WRT1900ACS 1.6Ghz. I found it at Fry's for ~$130. Even though that is triple what I paid for the ASUS, it may be my only solution. Does anyone have any thoughts on this choice?
>>>>>>>>>>>>>>
Oh well, it appears that I will be keeping the ASUS RT-AC56R. Now to get back and learn IF this can be overclocked the same way (if not the same level) as the RT-AC56U. . .
I will try the Merlin firmware and see if the VPN speeds differ. I am by no means wedded to dd-wrt, it is just the one I have used for years.
>>>>>>>>>>>>>>>
OK, I've been running Merlin 380.65 for a week. But it appears that this router cannot overclock unless I enter the danger zone and change the cfe. The sticker and the login screen say 56R but the board says 56U rev 2.20. I guess that is just the way it is done. I have cfe 1.0.2.7 (US), so I am out of luck. Still, a nice router. When it was running dd-wrt, the 2.4 Ghz band has problems and the led light for that bandwidth stayed dark. It appears to work fine w/ Merlin FW. I am not afraid to toy with it IF I knew that the cfe could be downgraded.
 
Last edited:
Hey, this thread is long and I've been reading a lot on it. I have a RT-AC56R rev 2.20. I now have a fan and I'm ready to overclock. I'm running the latest merlin firmware 380.69

26af9999-6538-49d4-a5d2-1aae7ebb4766.png


The main cpu is running between 50 and 55 celcius.

I've read that some stuff changed during the years but that's all mixed up and i cant really understand what changed. I don't really want to brick it, what are my options if i do.

Is rev 2.20 able to run 1200 / 800 stable or should I aim for something else.
 
can I just do what is written on page 1 in this thread? if it doesnt boot, can i just reset it on the modem itself, I saw people needing a serial cable to unbrick but i dont know what to do with that. i wont go above 1200/800 anyway
 
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For some reason, i cant go to this page with the last merlin, http://192.168.1.1/Tools_RunCmd.asp

I'm looking for help since this thread is old, but i got a shirt reply....... I know how to OC a CPU.......


HOW TO OVERCLOCK RT-AC56U

1. Navigate to http://192.168.1.1/Tools_RunCmd.asp

2. in the cmd window, copy paste/enter:
nvram set clkfreq=1200,800 - this will set CPU clock to 1200MHz and memory to 800 (for comparison - the stock is 800/533)

nvram commit && reboot

Warning: your router may hang at this point. Let it stay for couple minutes, if it does not come back, power cycle.
If you cannot get the router back after power cycling, follow to restore procedure outlined above

3. After successful reboot, you can check the clocks in the UI:
http://192.168.1.1/Tools_Sysinfo.asp

CPU
CPU Model ARMv7 Processor rev 0 (v7l) - (Cores: 2)
CPU Frequency 1200 MHz
CPU Load Average (1, 5, 15 mins) 0.09, 0.07, 0.05
 
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