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Memory voltage on AM3 motherboards

Last response: in Memory
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August 5, 2010 3:39:36 PM

Most AM3 motherboards seem to state a 1.5v memory voltage. However for DDR3nearly all DDR3 seems to be rated as 1.65v, with a fair few being higher.

Does this basically mean that the vast majority of memory is not fully compatible with most AM3 systems? Can the memory run at it's rated speed and timings at 1.5v, or are all AM3 motherboards (and CPU's I guess since its an integrated controller) able to run at these higher voltages perfectly fine (and would doing so break the warranty?)?

I looked in the BIOS of someone running some crucial 1.65v 1333MHz CL7 on a GA-870A-UD3 motherboard (1.5v) and it seemed that it was running (in auto) 1.5v and CL9. Is this the reality of AM3 systems or just a bad auto mode on that motherboard/bios?
August 5, 2010 4:34:41 PM

The recommended voltage is decreased in RAM and in these new processors to offset heat. Due to the higher speeds, more heat is generated. To offset this additional heat, the module manufacturers have solved this problem by lowering the voltage.

The 1.65volts will work fine, but it will simply run a little hotter. If you plan to increase the voltage or speed later, you should look into 1.5 volts.
August 5, 2010 6:11:29 PM


So ok, but given how the motherboards all just say "1.5v", how high can they safely go in your average system (ie rear fan, front fan, stock CPU cooler), and is there any protection at all (I've read that increasing ram voltage can damage the CPU with these integrated controllers)? I am not interested in over-clocking here, just if I can run the commonly available 1.65v memory at its rated voltage, speed and timings (ie CL7 instead of CL9 in the computer I looked at), and why is RAM like this, CPU's for example in auto mode go straight to the clock their meant to by default?
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