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under clocked/volted 125 watt phenom 2 on a 95 watt biostar a770e

post #1 of 2
Thread Starter 
Does anyone have any experience trying to boot a 125 watt cpu on a a770e (http://www.biostar.com.tw/app/en/mb/introduction.php?S_ID=469)? Does the bios not post or does it just underclock it/have issues under load?
post #2 of 2
BIOS support of this motherboard limits to 95watt CPU only, but if you install a 125watt cpu then it should work like most previous low end motherboard did (like ASUS m4a78lt-m-le). You will only be notified during POST that 'CPU is not Supported', but it will work.

Power circuitry of this motherboard is only designed for 95watt CPU. And according to AMD's power and thermal data sheet, all AM3/AM2+ CPU of 95watt TDP and 125watt TDP need 80Ampere and 110Ampere current respectively.
And we know the formula that power consumption in watts is equal to the voltage multiplied by current (Watt = volt*ampere).
Theoretically 125watt CPU at default frequency will need 1.136volt (125W / 110A). But in real world 125watt CPU runs at 1.296volt (to maintain stability).

Now the question is how much undervoltage will be required to run a 125w CPU in a 'Motherboard that can only support 95Watt CPU' (to run safely) and also without having CPU throttling to lower frequency at full load ???

As we know all 95watt CPU need is 80ampere current to operate optimally, and once again theoretical voltage of 1.1875Volt (95W / 80A) is needed. I believe 1.1875 to 1.250v undervoltaging will be enough.

After applying this voltage you will have to run stability test to see whether system crashes or not in undervoltaging situation. Use AMD Overdrive stability test and if it not shows any error within one hour, then you can safely run this 125watt cpu in your motherboard for 24/7.
Edited by sumitlian - 3/3/12 at 3:48am
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Haswell i3
(18 items)
 
  
CPUMotherboardGraphicsRAM
Core i3-4150 @ 3.5 GHz Asus B85M-G Rev 1.01, Bios: 2501 AMD Radeon HD 7850 ♥ 1GB 2x 4GB DDR3 1600 MHz CL9 
Hard DriveHard DriveHard DriveOptical Drive
Samsung 750 EVO 250GB Seagate Barracuda 1TB 7200.14 Seagate 500 GB 2.5" Samsung DVD/RW 
CoolingOSMonitorKeyboard
Corsair H70 Windows 10 64 bit Samsung A300N 20" 1600 x 900 60Hz 5ms 19Watt PS/2 Microsoft Wired Keyboard 500 
PowerCaseMouse
Corsair TX850 V2 CoolerMaster Elite 430 Black Logitech M170 
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