An OpenWRT forumer pepe2k (his blog www.tech-blog.pl) created a Firmware Recovery uboot here (if you like his work please donate).
From my experience with the AR9344 SoC I know that maximum possible clockspeed for AR9344 varies a lot.
I have a unit which can do a maximum of 700MHZ and another unit which can do a maximum of 740MHZ, so for this share I only shared a bootloader copy clocked at 600MHZ, if you want to try higher value you have to built the bootloader yourself.
The reason why I chose 600MHZ is because a Mikrotik Router using the same AR9344 is also clocked at 600MHZ CPU 400MHZ RAM and 200MHZ AHB so it should be safe.
Another issue is that some AR9344 routers come with low grade RAM as a result when you perform memtester, a utility that read & write bit patterns to RAM, to detect RAM errors it will fail. The default RAM clock is 450MHZ but it seems to be too high for certain brands of RAM.
A solution to this is to decrease the RAM frequency of 400MHZ.
I have build a special openwrt image to unlock write access to uboot so you can write the uboot image to the uboot partition.
Please remember to flash the normal image after you are done to write-protect the uboot from any accidental writes.
I have 2 images for download here
- Uboot with 600MHZ Overclock 450MHZ RAM 225MHZ AHB for routers without low grade RAM
- Uboot with 600MHZ Overclock 400MHZ RAM 200MHZ AHB for routers without low grade RAM as a fix to units with memtest errors
If you do not feel confident please do not attempt it.
As for how to test for RAM error:
- Connect your Router to Internet
- ssh into the router
- opkg update
- opkg install memtester
- memtester 32M (to test 32MB of memory)
After you flash the bootloader there will be a failsafe page where you can upload Atheros Radio Test (ART) Partitions, Firmware Image and bootloader if you press and hold the reset button after 4 light flashes from power on.