Can you overclock CPU on Asus RT-N66U?

[Dasto]

Firstly I have to say I think the Merlin Firmware is brilliant.

I was wondering if there is a way to overclock the router CPU through Merlin?
When router CPU is running at 99% the temperature stays static at 45 degrees Celsius.

Background to my question...

I have been trying to get faster VPN speeds on my ASUS RT-N66U when running through OpenVPN in Merlin. Between myself, ExpressVPN and VyprVPN we worked out that the bottleneck was my routers CPU. With VPN on router and I run speedtest.net my router CPU goes from 1% --> 99%. Without VPN CPU goes from 1% --> 18%. So on my 150mb down fibre I get 10mb down when VPN is on. I tried changing encryption from 256 to 160 but only a 3mb down increase. I tried PPTP and no difference. When running OpenVPN software on computer I get 60 to 90mb down.

That is why I would like to look at overclocking the cpu to see if I can get vpn speed up closer to 20mb down safely. I am running my Asus RT-N66U with Merlin Firmware version: 380.64_2 .

Any advice would be greatly appreciated.

 

[joegreat]

Can you overclock CPU on Asus RT-N66U?

Yes, you can! I also do it with my N66U...

Add the following lines into the user script service-stop:

#!/bin/sh

# set clkfreq (due to change in CFE/NVRAM handling by ASUS)
nvram set clkfreq=662,331,165
nvram commit​

You can choose other (lower) values from the list:

/* cpu, ddr, axi, proc_PLL, */
{ 200, 100, 50, 0xc0011080, },
{ 300, 150, 75, 0xc00110c0, },
{ 400, 200, 100, 0xc0011100, },
{ 500, 250, 125, 0xc0011140, },
{ 600, 300, 150, 0xc0011180, },
{ 632, 316, 158, 0xc00157e8, },
{ 650, 325, 162, 0xc00111a0, },
{ 662, 331, 165, 0xc00111a8, },​

But keep in mind that the poor MIPS-CPU of the N66U does not give you great performance for VPN-Traffic...

Only with an overclocked ARM-CPU you get more throughput - as discussed already several times in the forum.

 

[MikeW]

joegreat has already posted overclocking instructions, but suffice to say that you're not likely to get anywhere close to a 20Mbps VPN connection. My 1000MHz dual-core RT-AC68U router is CPU limited and gets just over 20Mbps, and I doubt your router can even operate at the 1000MHz processor speed without overheating.

 

[Dasto]

Yes, you can! I also do it with my N66U...
But keep in mind that the poor MIPS-CPU of the N66U does not give you great performance for VPN-Traffic...
Only with an overclocked ARM-CPU you get more throughput - as discussed already several times in the forum.

Thank you for quick reply. I don't normally change these settings.
Do I need to go to Administrator --> System, and enable 'Enable JFFS custom scripts and configs' ?
Sorry to ask but my Wife will kill me if the WiFi goes down for longer than 2minutes .

 

[pete y testing]

but my Wife will kill me if the WiFi goes down for longer than 2minutes

and what will she do when you fry the router because its overclocked ? divorce perhaps !!!!:-(

if you want faster vpn get a better and faster cpu router

 

[joegreat]

Do I need to go to Administrator --> System, and enable 'Enable JFFS custom scripts and configs' ?
Sorry to ask but my Wife will kill me if the WiFi goes down for longer than 2minutes .

Yes, you have to enable JFFS user scripting as described in the wiki from Merlin and reboot it!

And I fully understand that you need to find time when your wife is not around to work on your router config!

 

[mstombs]

On the N66 don't you have to check and update cfe version to allow overclocking?

https://www.snbforums.com/threads/cfe-bootloader-update.8259/

Definitely not something you want to rush to do!

I remember doing this a while ago, but didn't find the 10% overclock worth the potential life expectancy/stability risk.

 

[joegreat]

On the N66 don't you have to check and update cfe version to allow overclocking?

Good point!
I updated the CFE long time ago: Bootloader (CFE) 1.0.1.9

 

[unsynaps]

Yes, you can! I also do it with my N66U...

Add the following lines into the user script service-stop:

#!/bin/sh

# set clkfreq (due to change in CFE/NVRAM handling by ASUS)
nvram set clkfreq=662,331,165
nvram commit​

You can choose other (lower) values from the list:

/* cpu, ddr, axi, proc_PLL, */
{ 200, 100, 50, 0xc0011080, },
{ 300, 150, 75, 0xc00110c0, },
{ 400, 200, 100, 0xc0011100, },
{ 500, 250, 125, 0xc0011140, },
{ 600, 300, 150, 0xc0011180, },
{ 632, 316, 158, 0xc00157e8, },
{ 650, 325, 162, 0xc00111a0, },
{ 662, 331, 165, 0xc00111a8, },​

But keep in mind that the poor MIPS-CPU of the N66U does not give you great performance for VPN-Traffic...

Only with an overclocked ARM-CPU you get more throughput - as discussed already several times in the forum.

Wait. Why do you put it in service-stop? That is usually when the router is shirtting down. It needs to go in init-start at the earliest.

 

[joegreat]

Wait. Why do you put it in service-stop? That is usually when the router is shirtting down. It needs to go in init-start at the earliest.

He, he, he! Good thinking but wrong result:
The router set's the CPU clock speed AT boot - any user script runs far, far to late - and you can not change the speed after boot!

So: if the NVRAM values are set AT shout down to the higher value it will use them at boot... got it?

 

[netware5]

Firstly I have to say I think the Merlin Firmware is brilliant.

I was wondering if there is a way to overclock the router CPU through Merlin?
When router CPU is running at 99% the temperature stays static at 45 degrees Celsius.

Background to my question...

I have been trying to get faster VPN speeds on my ASUS RT-N66U when running through OpenVPN in Merlin. Between myself, ExpressVPN and VyprVPN we worked out that the bottleneck was my routers CPU. With VPN on router and I run speedtest.net my router CPU goes from 1% --> 99%. Without VPN CPU goes from 1% --> 18%. So on my 150mb down fibre I get 10mb down when VPN is on. I tried changing encryption from 256 to 160 but only a 3mb down increase. I tried PPTP and no difference. When running OpenVPN software on computer I get 60 to 90mb down.

That is why I would like to look at overclocking the cpu to see if I can get vpn speed up closer to 20mb down safely. I am running my Asus RT-N66U with Merlin Firmware version: 380.64_2 .

Any advice would be greatly appreciated.

The following answer is based on my long experience since 2013 of running overclocked RT-N66U as OpenVPN server:

1. Yes, you can overclock the router. The instructions how to do have been already posted by other members.
2. Yes, the overclocking will speed-up your connection, but not so much - no more than 10 %, as the safe overclocking is limited to 662 MHz.
3. The speed depends on encryption - 128 AES is faster then 256 AES. The maximum reported speed for RT-N66U is around 22-26 Mbps according to my memories. To check the exact results, do some search in the forum to find the tests posted by @RMerlin a few years ago. You can find there different test results for different configurations.
4. Here are the results for my RT-N66U with AES 256 encryption. If you use 128 you may have better results:

without overclocking - approx 12 Mbps
with overclocking - approx 14 Mbs
ISP line connection 50 Mbps.

Please note, that I am using TAP, so the router encapsulates an Ethernet frame and the payload is slightly larger than for TUN mode. So with TUN you may benefit slightly increase of the speed.

And just one more comment: You should not try to compare the OpenVPN performance of ANY consumer or SOHO router with ANY PC. They are incomparable. The PC will always win, with several rounds

 

[heysoundude]

Yes, you can! I also do it with my N66U...

Add the following lines into the user script service-stop:

#!/bin/sh

# set clkfreq (due to change in CFE/NVRAM handling by ASUS)
nvram set clkfreq=662,331,165
nvram commit​

You can choose other (lower) values from the list:

/* cpu, ddr, axi, proc_PLL, */
{ 200, 100, 50, 0xc0011080, },
{ 300, 150, 75, 0xc00110c0, },
{ 400, 200, 100, 0xc0011100, },
{ 500, 250, 125, 0xc0011140, },
{ 600, 300, 150, 0xc0011180, },
{ 632, 316, 158, 0xc00157e8, },
{ 650, 325, 162, 0xc00111a0, },
{ 662, 331, 165, 0xc00111a8, },​

But keep in mind that the poor MIPS-CPU of the N66U does not give you great performance for VPN-Traffic...

Only with an overclocked ARM-CPU you get more throughput - as discussed already several times in the forum.

Is it necessary to include the 165 after 662, 331? what's that 3rd number for?

 

[joegreat]

Is it necessary to include the 165 after 662, 331? what's that 3rd number for?

Yes it is: check your self with command line nvram get clkfreq and you see that all three values are there.
The third value is for AXI - I assume it has to do with chipset timing.

 

[heysoundude]

I will amend my script. Thank you.

 

[heysoundude]

need help clearing the cobwebs on this -
ssh into router, cd /jffs/scripts, nano services-start, copypasta, exit, save, reboot, verify?

 

[Wallace_n_Gromit]

Yes, you can! I also do it with my N66U...

Add the following lines into the user script service-stop:

#!/bin/sh

# set clkfreq (due to change in CFE/NVRAM handling by ASUS)
nvram set clkfreq=662,331,165
nvram commit​

You can choose other (lower) values from the list:

/* cpu, ddr, axi, proc_PLL, */
{ 200, 100, 50, 0xc0011080, },
{ 300, 150, 75, 0xc00110c0, },
{ 400, 200, 100, 0xc0011100, },
{ 500, 250, 125, 0xc0011140, },
{ 600, 300, 150, 0xc0011180, },
{ 632, 316, 158, 0xc00157e8, },
{ 650, 325, 162, 0xc00111a0, },
{ 662, 331, 165, 0xc00111a8, },​

Do those lower values apply to the RT-AC68U? If not do you have a list of the lower underclocking values?

 

[Grisu]

Do those lower values apply to the RT-AC68U? If not do you have a list of the lower underclocking values?

RT-AC68U possible clocks: CPU 800/1000/1200/1400 RAM 533/666/775/800