Direct media interface

[hannibal2469]

correct me if i am wrong,
but if dmi consists of 4 lanes of pci express connecting cpu to southbridge then wont the pci e lanes, usb, sata all of which are connected to the southbridge be bottlenecked by the dmi speed.

 

[Wisecracker]

I don't believe *speed* is the term you are looking for --- consider *bandwidth*

Theoretically (and genericly, with both AMD and Intel), northbridge<--->southbridge bandwidth is now around 20Gb/s --- hard to find the volume I/O on the desktop to fill that pipe.

There are all kinds of qualifications and permutations I could add on the differences between hardware and tech generations, but the best thing to say is ...

""Don't worry about it""

 

[hannibal2469]

actually i just want know more about the various cpu-chipset interconnects esp DMI

 

[hannibal2469]

help

 

[hunter315]

The PCI-E lanes are connected directly to the CPU not to the PCH(south bridge), as is the memory, so they do not fill up those 4 PCI-E lanes, also PCI-E 2.0 lanes have an obscene amount of bandwidth for USB and SATA ports and they will never all be running at full capacity anyway so its not a real concern.

 

[hannibal2469]

ok thx got my answer but i think there are a few addtional lanes offered by the chipset in addition to those directly conected to the cpu
also was i right about DMI being 4xpcie 2.0

 

[ElMoIsEviL]

ok thx got my answer but i think there are a few addtional lanes offered by the chipset in addition to those directly conected to the cpu
also was i right about DMI being 4xpcie 2.0

Yes the South Bridges often come equipped with a few PCIe lanes. These lanes generally provide for ~ 6-8 PCIe x1 1.1 or 2.0 slots on the motherboard (in some cases full PCIe x16 slots are physically found on the motherboard while they can only physically provide around PCIe x4 worth of copper connectors/bandwidth).

Also the Intel DMI bandwidth found on the P67 (which connects the CPU to the Southbridge) offers 20Gb/s and not 20GB/s. This gives you ~ 2.5GB/s of actual bandwidth. It can become saturated in some rare instances.

The 8 PCIe 2.0 Lanes can consume up to 4GB/s (bi-directional 8GB/s) of bandwidth. Somehow 2.5GB/s seems like a bottleneck.

 

[hannibal2469]

Yes the South Bridges often come equipped with a few PCIe lanes. These lanes generally provide for ~ 6-8 PCIe x1 1.1 or 2.0 slots on the motherboard (in some cases full PCIe x16 slots are physically found on the motherboard while they can only physically provide around PCIe x4 worth of copper connectors/bandwidth).

Also the Intel DMI bandwidth found on the P67 (which connects the CPU to the Southbridge) offers 20Gb/s and not 20GB/s. This gives you ~ 2.5GB/s of actual bandwidth. It can become saturated in some rare instances.

http://i.neoseeker.com/a/Intel_Sandy_Bridge_P67/p67.png

The 8 PCIe 2.0 Lanes can consume up to 4GB/s (bi-directional 8GB/s) of bandwidth. Somehow 2.5GB/s seems like a bottleneck.

right, got my answer
thank you so much