QPI on i5 750

[mbbk1992]

I understand that the i5 series got a DMI bus instead og a QPI like the i7. But then why does CPU-Z say that my QPI freq. is 2400 or something(i dont have access to my rig right now so im not sure about the exact speed)?

Mathias

 

[LePhuronn]

Because although the technology is different QPI and DMI serve the same purpose and it seems that a lot of people think the terms are interchangeable.

More than a few BIOSes on P55 motherbaords list QPI instead of DMI, and I wouldn't be surprised if CPU-Z is just doing the same thing.

 

[yannifb]

Huh... I knew the i5 had something different but I didn't realize thats what they meant by DMI. So is DMI faster that QPI? What does it stand for? Why is it used instead?

Well basically i just want to know more about it, lol.

 

[EXT64]

Here it is off wiki

http://en.wikipedia.org/wiki/Direct_Media_Interface

http://en.wikipedia.org/wiki/QPI

From the looks of it, it (DMI) was the link between the NB and SB on the old boards, so it did not need to be very fast. QPI on the X58 does everything, so it must be much faster (on 1156, PCI-E lanes go directly from CPU to video cards).

 

[mbbk1992]

The "lack" of speed compared to the QPI is just okay since the DMI connect's the "low speed devices" from the p55 chip to the CPU...

 

[Devastator_uk]

these two links are helpful (well helped me understand it):

http://en.wikipedia.org/wiki/File:X58_Block_Diagram.png

http://en.wikipedia.org/wiki/List_of_Intel_chipsets#5_Series_Chipsets

Basically with i5s the Northbridge is build into the CPU, shouldn't really in itself affect performance as I'm guessing there is a kind of internal QPI, however it seems like the main limitation for those that have SLI/Crossfire is the limited number of PCIe lanes, but for those with just one card it shouldn't really matter.

 

[mbbk1992]

Besides Really large resolutions and quad cf/sli (like an 5970), the 16x limit is not going to affect the performance....