What is PLL and VTT?

Hi,
I've read about these options and I never really had a clear understanding on what they actually do and I would like a simplified (yet accurate) explanation on what VTT and PLL are. What are each of their functions and how do they relate to overclocking? Is there only one PLL andVTT voltage or are there more than one for different functions on the cpu/mobo?


P.S: Im not planning on messing with these in my bios, its just for educational purposes only so please no answers like "Don't mess with it" Thanx in advance :bounce:
5 answers Last reply
More about what
  1. PLL is phase locked loop. I'm not 100% on how it works but I know it's something to do with syncing the sine wavelengths of the power coming into the PC with the motherboard's power... or something.

    VTT I don't have any idea what the acronym might stand for, however, it is also comonly refered to as IMC which stands for Integrated Memory Controller. This is somewhat like a northbridge type thing, except not. It's onboard the chip but it handles a lot of information. This is just my experience but it seems when overclocking, if you raise FSB or Base Clock you'll need at least a bit more VTT - sometimes no matter how much Vcore you give, it won't get stable without some more VTT. I also noticed that additional VTT could offset the Vcore and therefore adding VTT would allow you to lower the Vcore a tad as well.

    Hope that helps a bit.
  2. Thanx for that, it was a good start to my understanding.


    What happened to everybody? 50 views and only 1 reply :heink:
  3. aaron686 said:
    P.S: Im not planning on messing with these in my bios, its just for educational purposes only


    aaron686 said:
    What happened to everybody? 50 views and only 1 reply


    You're not planning on using the information, but you want people to take the time to explain it to you, most of us don't mind helping someone to attain their OCing goals, but to educate you just to appease your curiosity, is Google territory!

    Try starting your education from the link below, it contains additional links to further your understanding, then you can move on to dedicated overclocking guides, you know, just for educational purposes only.

    http://www.anandtech.com/show/2500/17

    There's really only so far it can be simplified for you.

    http://www.overclock.net/intel-cpus/605848-i5-i7-lga-1156-overclocking-guide.html
  4. 4Ryan6 said:
    You're not planning on using the information, but you want people to take the time to explain it to you, most of us don't mind helping someone to attain their OCing goals, but to educate you just to appease your curiosity, is Google territory!


    The reason why I added that part was because I know that if i didn't, I would get replies such as "Don't mess with it" and people would ask me what OC I have, what I want to obtain etc which is not the path i want to go down, and as I said, I did google and there is either a uber complex explanation or a extremely brief, non-informative section tucked away. After all, this is a tech forum and sharing information never hurts and doesn't necessarily have to be put into practice. I know I will use the knowledge sometime in the near future when i'm ready.


    Edit: thank you for the link, although it doesn't explain what it does exactly, its a good start, appreciated.
  5. Here's another good reference, written about the Lynnfield architecture (i5 750): http://www.bit-tech.net/hardware/cpus/2009/09/21/overclocking-intel-s-core-i5-750/2

    I linked to page 2 which discusses the V you asked about, but you'll want to read page 1 too.

    EDIT: Another good article for discussing V especially in terms of OCing: http://www.xbitlabs.com/articles/mainboards/display/asus-p7p55d-deluxe.html
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