QPI / Vtt voltage ..what does it do ?

karlos103 · 15 Jul 2009 at 19:06

Hi all

what does "QPI / Vtt voltage" do ...can it be tweaked to improved performance ?
mine is set at 1.175 (auto) ...someone said he tweaked his to increase bootup time ...could this be right ?

Any help most appreciated
karl

Geekazoid · 15 Jul 2009 at 19:39

QPI stands for Quick Path Interconnect intel intergrated this into its new chips to bypass the FSB... basically helps cpu communicte with the X58 mobo... cpu vtt = fsb voltage if you're OC your CPU to the extreme FSB such as >400 you need to increase this cpu vtt to make your rig more stable. however im puzzled on the i7 the FSB is no longer in use (BLCK on i7) hence the use of VTT volage is a bit of a mystery to me... but i aint herd of computers booting quicker increasing the values...

[edit] my qpi link speed is at x36 which connects the cpu at 7.2ghz with the X58 chipset
and the QPI/VVT set at 1.33v

karlos103 · 15 Jul 2009 at 21:12

so it it worth upping my qpi voltage to say 1.3 ??

karlos103 · 15 Jul 2009 at 22:06

actually just tried it at 1.315 volts ...run prime and crashed (bsod) withing 3 seconds of running it .
just set it back to auto and prime running fine now

boldenc · 16 Jul 2009 at 02:15

Auto Value in QPI/VTT with gigabyte is hidden, to make sure the correct value used, check ET6, it will show what is the current QPI/VTT

Geekazoid · 16 Jul 2009 at 02:18

actually just tried it at 1.315 volts ...run prime and crashed (bsod) withing 3 seconds of running it .
just set it back to auto and prime running fine now

some CPU like QPI-VVT voltage to be high some like it low... you have to fine tune as every chip is different if yours is running stable on auto leave it at that...

karlos103 · 16 Jul 2009 at 17:03

Geekazoid said:
some CPU like QPI-VVT voltage to be high some like it low... you have to fine tune as every chip is different if yours is running stable on auto leave it at that...

yes i know what you mean ...if it aint broke , then dont try and fix it .
All is well with it using prime ...so i won't mess ...only asked as someone said it increased their boot time when they increased the voltage ...
Ow well thanks everyone for the info
Karl

Bradley8988 · 16 Jul 2009 at 17:32

Some set ups like less voltage and are un stable if you raise it and some like VVT over 1.4v and crash with any lower. Its the same with all intel chips pretty much.

PaulyD · 16 Jul 2009 at 17:41

Qpi is the amount of bandwidth shared to the motherboard in the system, overclocking your CPU by bclk will also increase the qpi, for example

133 (bclk) x 18 (or 36 - standard multi) = 2394 (2400mhz or 4.8 GT/s when doubled)

however upping bclk ups this as well, you can drop the multi lower to keep this in check if you want to though. When raising qpi you will also need to increase the vtt voltage that controls it

guessing the reason why the other persons pc booted quicker was because the IMC wasn't getting enough juice.

Also remember to keep vtt within 0.5v of your vdimm

Meridian · 16 Jul 2009 at 18:43

Geekazoid said:
some CPU like QPI-VVT voltage to be high some like it low... you have to fine tune as every chip is different if yours is running stable on auto leave it at that...

In my experience the issue is the motherboard not the CPU. My P6T has run a C0 and a D0 and both require stupidly high settings for stability at even modest overclocks: over 1.50V. By constast, my Gigabyte UD5 gets upset if it goes over 1.30V.

M