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Six A75-Based Motherboards For AMD’s A8 And A6 APUs

Overclocking

BIOS Frequency and Voltage settings (for overclocking)
ASRock A75MAsus F1A75-M ProECS A75F-M2
CPU Base Clock100-136 MHz (1 MHz)90-300 MHz (1 MHz)Not Adjustable
CPU Multiplier16x - 47x (1x)8x - 47x (1x)1x - 47x (1x)
GPU Frequency253-800 MHz (4.5 MHz)NoneNot Adjustable
DRAM Data Rates800-1866 MT/s (266 MHz)800-1866 MT/s (266 MHz)800-1866 MT/s (266 MHz)
Core Voltage0.60-1.86 V (12.5 mV)0.80-1.70 V (12.5 mV)Not Adjustable
GPU Voltage0.60-1.86 V (12.5 mV)1.20-1.80 V (10 mV)Not Adjustable
APU VDDP1.11-1.80 V (15 mV)0.80-1.55 V (12.5 mV)Not Adjustable
FCH Voltage1.10-1.40 V (10 mV)1.10-1.40 V (10 mV)Not Adjustable
DRAM Voltage1.30-1.97 V (52 mV)1.35-2.30 V (10 mV)Not Adjustable
CAS Latency5-14 Cycles5-14 Cycles4-12 Cycles
tRCD5-14 Cycles5-12 Cycles5-12 Cycles
tRP5-14 Cycles5-14 Cycles5-12 Cycles
tRAS15-36 Cycles15-36 Cycles15-30 Cycles
BIOS Frequency and Voltage settings (for overclocking)
Gigabyte A75M-UD2HJetway TA75MGMSI A75MA-G55
CPU Base Clock100-500 MHz (1 MHz)Not Adjustable100-131 MHz (1 MHz)
CPU Multiplier8x - stock  (1x)8x - 47x  (1x)16x - 40x (1x)
GPU Frequency300-2000 MHz (1MHz)Not Adjustable400-2000 MHz (1MHz)
DRAM Data Rates1066-1866 MT/s (266 MHz)800-1866 MT/s (266 MHz)800-1866 MT/s (266 MHz)
Core Voltage-0.60V to +0.40 V (25 mV)Not Adjustable1.41-2.00 V (10 mV)
GPU Voltage-0.60V to +0.30 V (25 mV)Not Adjustable1.18-1.50 V (10 mV)
APU VDDP0.73-1.84 V (5 mV)Not AdjustableNot adjustable
FCH Voltage0.63-1.74 V (5 mV)Not AdjustableNot adjustable
DRAM Voltage1.03-2.14 V (5 mV)Not Adjustable1.37-1.90 V (10 mV)
CAS Latency5-14 CyclesNot Adjustable5-14 Cycles
tRCD5-14 CyclesNot Adjustable5-14 Cycles
tRP5-14 CyclesNot Adjustable5-14 Cycles
tRAS15-36 CyclesNot Adjustable15-36 Cycles

ASRock, Gigabyte and MSI have addressed Chris’ unsuccessful Llano overclocking efforts with changes that allow the SATA controller to continue functioning at higher base clock rates. The analog VGA output still ceases to operate at reference clocks beyond 107 MHz, but integrated digital outputs and discrete graphics cards function normally. This is just one more reason for us to ditch VGA altogether.

With SATA controller functionality no longer an issue, our SSD worked even with Gigabyte’s A75M-UD2H running at 144 MHz. Of course the CPU wasn’t as forgiving, and we did have to lower its multiplier to reach this high reference clock.

A 143 MHz base clock worked at the CPU’s stock (maximum) multiplier, allowing Gigabyte’s A75M-UD2H to push an impressive 3.7 GHz CPU clock out of our lowly A6-3650 APU.

AMD’s memory overclocking issues appear to be a thing of the past, as ASRock’s A75M pushed our DDR3-2200 memory past the rating of its intended (P67-based) platform.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.