AMD A6-3650 2.6GHz Llano APU ReviewMon, Jul 18, 2011 - 12:00 AM
AMD A6-3650 APU Overclocking
Overclocking greatly varies due to what hardware is being used and
who is doing the overclocking. Always remember that no two pieces of
hardware will perform the same, so our results will differ from what you
might be able to get. The AMD retail boxed CPU cooler was used for
overclocking, so we’d expect this overclock to be easily reached by anyone!
The AMD A6-3650 APU starts off at 2600MHz with a base clock of 100MHz with a multiplier of 26. This is a locked multiplier, so you can lower the multiplier in the BIOS, but you can not increase it. That means for overclocking we are limited to just increasing the base clock frequency in the motherboards BIOS.
With everything left to default in the BIOS and by just raising the back clock frequency we were able to reach 117MHz and then we hit a wall. The Gigabyte GA-A75M-UD4H motherboard uses the VGA display output as the primary video connection and that is what we were using. At any clock frequency over 117MHz our monitor would get an ‘out of scan range’ error. We had to clear the CMOS each time this happened until we finally went into the BIOS and enabled the dual link DVI connector. Once we were off the analog output and on the digital output we were able to continue increasing the bus speed without having to increase the voltage.
We didn’t get much further though as at 119MHz baseclock the system started to blue screen when running full load benchmarks like Hyper Pi. So, 119MHz was the highest we could get the AMD A6-3650 APU on the Gigabyte GA-A75M-UD4H motherboard. Most people would stop here as this is a 500MHz increase, but we wanted more. The stock CPU Voltage on the Gigabyte GA-A75M-UD4H is 1.4125V, so we bumped up the voltage by 0.050V to 1.4625V and tried to keep going.
By just increasing the CPU voltage up to 1.4625V we were able to increase the base clock up to 126MHz with full stability. Anything over 126MHz and the system would start to blue screen again. This overclock puts the system at 3.3GHz, which is roughly 600MHz faster than the stock clocks of 2.6GHz. When we increased the voltage and went over 119MHz all of the USB 3.0 ports on the Gigabyte GA-A75M-UD4H motherboard stopped working for some reason. That means both Analog Video and SuperSpeed 3.0 were not functioning properly.
To keep overclocking we increased the voltage by 0.150V, which put us at 1.5625V on the CPU.We were able to reach 145MHz with rock solid stability. At this clock speed we could run Hyper Pi, 3DMark Vantage and even Prime95 without hitting and blue screens. The BIOS showed a temperature reading of 49C and that was on the stock AMD heatsink. Running a 145MHz baseclock put the A6-3650 at 3.77GHz and really helped performance. For example the stock 1M Super Pi average score was 28.548 seconds and now it is just 20.880 seconds. A rather significant change!
Our overall 3DMark Vantage score went from P3231 to P4208, which is a pretty decent gain for this benchmark that is rather GPU heavy. The CPU score went from 9079 to 11677, which is fairly nice performance gain. Memory bandwidth was also improved as it went from 15.1GB/s to 18.2GB/s!
The highest speed that we could run the AMD A6-3650 was with the base clock set to 147MHz, which meant the CPU was running at 3822MHz. We could run several benchmarks at this speed, but it wasn’t fully stable. When we went to save screen shots we’d get the BSOD and the system would reboot. We tried increasing the voltage and also different base clocks, but we were hitting a wall and are content with calling this good enough for a processor review.
At the end of the day we were able to get to ~3.8GHz on the AMD A6-3650 APU with full stability and that is very impressive as we were on the stock AMD heatsink! For a $120 processor we found that the A6-3650 could provide hours of enjoyment and being able to crank up the clock frequency by 47% will bring a smile to your face even if you can only run a few benchmarks!.