Good morning,
After 6 months of using “1450 MHz with 0 over voltage” and “1475 MHz with 0 over voltage” overclocking settings for my 4 RPi’s 3 A+ it is important to report that even “1475 MHz with 0 over voltage” overclocking setting is unstable (up to 4 crash per machine during this 6 month period), but it does not crash as often as other more extreme overclocking settings. Once more, crash’s are not due to temperature but to system instability.
The only truly stable overclocking setting for RPi 3 A+, from my experience, is “1450 MHz with 0 over voltage”.
I hope this information is useful.
Best regards,
Paulo Reis