QPI and DRAM voltage question

Can someone explain QPI voltage and DRAM voltage under these circumstances:

I have 12GB of Corsair DDR3-1600 CAS8. Label says 1.65v Mobo is Asus P6T Deluxe v1

If I set the DRAM frequency to DDR3-1333 and everything else on AUTO, I get the following measurements using TurboV:

QPI/DRAM Core Volt = 1.20000v
DRAM Bus Voltage = 1.66v

If I manually set the DRAM bus voltage to 1.5v it reports 1.5v

If I want to run the RAM at DDR3-1600, I set the frequency to DDR3-1600 and leave everything else on AUTO, I get the following from TurboV:

QPI/DRAM Core Volt = 1.37500v
DRAM Bus Voltage = 1.66v

I can manually set the DRAM to 1.64v and it will report 1.64v but if I try to lower the QPI/DRAM Core Voltage to 1.2v, it fails to boot.

I am worried that the mobo is over-volting the QPI/DRAM Core Volt setting. What are 'safe' voltages if i want to run it at DDR3-1600? Can anyone recommend safe settings?

Thank you

The higher your DDR3 frequency, the more you'll need increased voltage for your uncore (which is labeled as the QPI voltage setting on ASUS boards).

That's the reason why (when increasing the speed from 1333 to 1600) AUTO settings will increase the QPI voltage.

It's also the reason why, when you manually adjust it to 1.2V with 1600 speed, it fails to boot.

With 6GB of RAM you might be able to get away with lowering that value, but 12GB puts a lot more stress on the uncore / memory controller.

sn0man said:

The higher your DDR3 frequency, the more you'll need increased voltage for your uncore (which is labeled as the QPI voltage setting on ASUS boards).

That's the reason why (when increasing the speed from 1333 to 1600) AUTO settings will increase the QPI voltage.

It's also the reason why, when you manually adjust it to 1.2V with 1600 speed, it fails to boot.

With 6GB of RAM you might be able to get away with lowering that value, but 12GB puts a lot more stress on the uncore / memory controller.

Click to expand...

Thanks for the information. Is this 'normal' for the mobo to do this? Is this safe?

Yeah, that's pretty much what AUTO settings do - crank everything up to where it's easily able to boot. You can see that from your little experiment of lowering the voltage yourself.

In terms of 'safety' for that setting, 1.375V isn't anything extreme. I believe Intel's max recommended uncore voltage is 1.35, but obviously the recommended settings get tossed right out the window when you start talking about overclocking.

1.4 and above isn't too uncommon, especially when you start talking about more than 6GB and/or speeds above 1600.

There's a huge thread regarding this voltage over at XS if you want to see how far those guys push it.

sn0man said:

Yeah, that's pretty much what AUTO settings do - crank everything up to where it's easily able to boot. You can see that from your little experiment of lowering the voltage yourself.

In terms of 'safety' for that setting, 1.375V isn't anything extreme. I believe Intel's max recommended uncore voltage is 1.35, but obviously the recommended settings get tossed right out the window when you start talking about overclocking.

1.4 and above isn't too uncommon, especially when you start talking about more than 6GB and/or speeds above 1600.

There's a huge thread regarding this voltage over at XS if you want to see how far those guys push it.

Click to expand...

Even if I set QPI to 1.35v Turbo V still reports 1.375v. I don't get it.

I wouldn't worry too much about that. Software reports of hardware voltage are notoriously inaccurate. And even so, like I said 1.375 isn't anything extreme.

If I use the XMP settings for my ram it sets the DRAM voltage to 1.66v, the QPI voltage to 1.35 and it will boot at DDR3-1600 settings. But TurboV still reports the QPI as 1.375v. I know you said that is ok but I am still a worry wart. This machine needs to last a while......

I'm assuming you're using 2 6GB kits. XMP settings don't really account for voltages needed when you're adding additional memory, so always make sure through memtest / Linx / IBT / etc. that first and foremost you're stable.

I understand your being a worrier. Check out that XS thread and you'll have a lot less to worry about once you see what those guys are running 24/7.

Yes 2 x 6GB kits. If it would just run at 1.35v for QPI i'd be less worried.

Thanks for answering my questions and the link. I will go check it out.