I installed Ubuntu Server 24.04 and had made changes to the file /boot/firmware/config.txt:
[all]
over_voltage=6
arm_freq=2850
7z test before overlocking:
7-Zip (z) 23.01 (arm64) : Copyright (c) 1999-2023 Igor Pavlov : 2023-06-20
64-bit arm_v:8 locale=C.UTF-8 Threads:4 OPEN_MAX:1024
Compiler: 13.2.0 GCC 13.2.0
Linux : 6.8.0-1008-raspi : #8-Ubuntu SMP PREEMPT_DYNAMIC Tue Jul 16 19:17:49 UTC 2024 : aarch64
PageSize:4KB THP:madvise hwcap:119FFF:CRC32:SHA1:SHA2:AES:ASIMD
LE
1T CPU Freq (MHz): 2180 2394 2394 2394 2394 2394 2394
2T CPU Freq (MHz): 200% 2384 200% 2391
RAM size: 3989 MB, # CPU hardware threads: 4
RAM usage: 889 MB, # Benchmark threads: 4
Compressing | Decompressing
Dict Speed Usage R/U Rating | Speed Usage R/U Rating
KiB/s % MIPS MIPS | KiB/s % MIPS MIPS
22: 10945 373 2853 10648 | 159223 393 3457 13584
23: 10225 378 2753 10419 | 158060 399 3431 13677
24: 9649 381 2721 10375 | 153815 396 3405 13498
25: 9553 378 2887 10908 | 150728 397 3380 13415
---------------------------------- | ------------------------------
Avr: 10093 378 2804 10587 | 155457 396 3418 13543
Tot: 387 3111 12065
real 0m36.790s
user 2m12.573s
sys 0m1.883s
7z test result after overlocking:
7-Zip (z) 23.01 (arm64) : Copyright (c) 1999-2023 Igor Pavlov : 2023-06-20
64-bit arm_v:8 locale=C.UTF-8 Threads:4 OPEN_MAX:1024
Compiler: 13.2.0 GCC 13.2.0
Linux : 6.8.0-1008-raspi : #8-Ubuntu SMP PREEMPT_DYNAMIC Tue Jul 16 19:17:49 UTC 2024 : aarch64
PageSize:4KB THP:madvise hwcap:119FFF:CRC32:SHA1:SHA2:AES:ASIMD
LE
1T CPU Freq (MHz): 2421 2844 2843 2843 2844 2844 2844
2T CPU Freq (MHz): 199% 2823 200% 2843
RAM size: 3989 MB, # CPU hardware threads: 4
RAM usage: 889 MB, # Benchmark threads: 4
Compressing | Decompressing
Dict Speed Usage R/U Rating | Speed Usage R/U Rating
KiB/s % MIPS MIPS | KiB/s % MIPS MIPS
22: 11806 382 3005 11485 | 188311 395 4066 16065
23: 10852 385 2871 11057 | 183935 398 4001 15916
24: 10143 384 2839 10906 | 178213 394 3967 15640
25: 10081 381 3018 11510 | 175262 396 3941 15598
---------------------------------- | ------------------------------
Avr: 10720 383 2933 11240 | 181430 396 3994 15805
Tot: 389 3463 13522
real 0m32.727s
user 1m58.614s
sys 0m1.781s
I use a small cooler with a small fan and overlock to 2.85G hz.
I also run stress to test tempture. Its max tempture was 67 C in my test. Before overlocking, the highest tempture was 60 C.
To sum up, in my test 2.85G is a safe speed. If you want to higher performance you can try. And give it a large cooler.