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Voltage difference between CPU VTT and RAM voltage?

  • Thread starter Deleted member 72990
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Deleted member 72990

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I've read a few times on these forums that CPU VTT voltage should not have a greater difference than 0.5v from the RAM voltage on Ivy Bridge CPU's. My VTT is like 1.05 and my ram voltage is 1.65, so that is a 0.6v difference. I never read why it should be less than 0.5v difference though - can somebody please enlighten me?
 
does this help at all, clipped from here: http://www.masterslair.com/vcore-vtt-dram-pll-pch-voltages-explained-core-i7-i5-i3 its older but explains it pretty clearly and if I understand it right its all to do with the IMC stability.

VTT (aka IMC, QPI/VTT, QPI/DRAM)
VTT goes by many names depending on what brand of motherboard you have, but it is the voltage for the Integrated Memory Controller (IMC) inside of the CPU. This controller speaks directly with the RAM, and as you increase the system's base clock rate ( BCLK), the IMC frequency also increases, so you'll have to up this voltage as you up BCLK.

The default VTT for Clarkdale and Lynnfield based processors is 1.1 V, and the absolute maximum (as specified by Intel) is 1.4 V.

DRAM / VDIMM
This voltage is directly fed to your RAM and will only need to be increased if you increase the speed of your memory or tighten its timings.

The default DRAM voltage for socket 1156 motherboards is 1.5 V, but the voltage you will actually use will depend on the specifications for your RAM. Intel's absolute maximum for this is 1.8 V, but they recommend that you keep it under 1.65 V.

Your DRAM voltage should never be more than 0.5 V above VTT, or it could cause system stability problems. Since the default VTT is 1.1 V, this means that your DRAM voltage shouldn't be higher than 1.1 + 0.5 = 1.6 V--unless you also increase VTT. So if you're using memory that has a default voltage of 1.65 V or you've overclocked to that amount, you should increase your VTT voltage to at least 1.65 - 0.5 = 1.15 V.
 
Thank! I haven't had any problems with stability until I start going over 4.7 GHz. I wonder if increasing VTT will help me squeeze out a little more MHz.
 
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