PCI-E 16 x2 Question

K

Kreator

Limp Gawd
Joined
Nov 17, 2005
Messages
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i had another thread about this earlier today however i am still unable to resolve it.

to rehash the issue... i recently swapped my 7800gtx to my lower PCI-E slot, verified that all jumpers are in the TOP position

however programs such as PCWizard 2006 and EVEREST display things such as this...


http://img79.imageshack.us/img79/9290/screen11sp.jpg

the @2 is what is bugging me

am i having a brain fart and its running at the full 16 width or am i missing something. details about my MB are below in sig...
 
its SLI compatable MB meaning theres 2x PCI-E, im not sure if its a true 16 or not...

the reason i dropped it down to the lower slot is because on the top one the end of the card hovers directly overtop of the northbridge fan...
 
but do you see how it says 16 at 2x though... does that mean its using 2 out of a potential of 16
 
In theory both the lanes share 16x bandwidth

If you were to throw an identical card in the first slot it will down clock to 8x per slot.

That is why yo uare seeing 16x
 
no you guys are missing what im saying....

i know it says it has 16 max but several things say 16x @ 2x...

meaning i think its only set to use 2x of the 16
 
from the last pic, it looks like your card is running in 8x mode. it looks like the second slot doesn't support 16x PCI-e.
 
how do you determine that?

it says max x16 right next to where it says its in x2
 
It says that the populated slot max link width is 8x. under where it is listed for the GTX, the card itself has a max of 16x which is in ( ), but it is only running at 2x right now. So it looks like the 2nd slot on your board has a total max of 8x, the card has a total max of 16x, and at the moment it is running at 2x.
 
.... dude theres no 8x anywhere on the pci-e slot that has the video card i have no clue where your getting this from
 
You're very rude,

I dont think any of us are inclined to help supposed know-it-all kiddies that slap everyone that tries to help.
 
regardless of what you think it was not meant to be rude simply stating that i do not see where he is pulling this from.
 
Kreator said:
.... dude theres no 8x anywhere on the pci-e slot that has the video card i have no clue where your getting this from
Click to expand...
Don't be rude. I found a page on google that will help you out.
 
Either you are blind, or don't know how to read. I went ahead and circled it for you.

The slot your card is plugged into only supports 8x PCI-e. Notice how it states that the 8x slot is the only one populated?

Your card supports up to 16x PCI-e.

Your card is currently running at 2x.

29765.jpg
 
ahhh see thats what i wanted to know... thanks man

i thought that might have been it but i wasnt sure....

is it possible 7800gtx uses slightly more than 8x but not a full 16x atm? since i switched it i just feel like i hit a couple stutters every now and then in games even though my frame rate never drops
 
In the slot that you have it plugged into, you won't get the full potential out of the card. It won't harm the card to have it over the northbridge.
 
aight cool

yea i just ordered a new lian li and all sorts of other things that will help me quite a bit so i intend on moving it back soon
 
Kreator said:
its SLI compatable MB meaning theres 2x PCI-E, im not sure if its a true 16 or not...

the reason i dropped it down to the lower slot is because on the top one the end of the card hovers directly overtop of the northbridge fan...
Click to expand...

There it is, problem solved or at lest explained.

Here's why. nForce4 SLI boards have two PCIe X16 slots that are wired to be two at x8 channels when in SLI mode. Because the nForce4 chipset only has a total of 20 lanes available, it can't have two x16 slots.

When you are not in SLI mode (2 @ x8), you'll have the following:

PCIe Slot 1 (closest to CPU), x16 channels.

PCIe Slot 2 (further down), x2 channels.

If you place the card in the second slot, it'll only have x2 channels available unless in SLI mode.
 
bLaCktIGErs91 said:
No, it's not. I can guarantee that. You're fine.
Click to expand...

True, just not at the full speed the card can do. His card won't be damaged, but it only has x2 channels available to it when in the second slot and not in SLI mode.

Without changing the SLI selector (BIOS on the latest boards but jumpers or a little simm card on the older boards from "non-SLI" to "SLI"), you don't get the x8 channels to the second PCIe slot. The slot has the same number of "pins" as a x16 channel slot, but it's only wired to max out at x8 in SLI, or only x2 in non-SLI (the rest are "rechanneled" over the SLI card to the first slot for a full x16 channels)

The Chipset is only capable of a maximum 20 channels, so unless you buy a board with the newer nForce4 SLI X16 chipset (both a north and south bridge solution instead of the single chip solution) you can't have two x16 slots. The newer boards based on that newer chipset can have two full x16 slots and are why they don't have any selector cards as no "lanes" need to be redirected.
 
You've got a standard SLI chipset. You're primary video card slot can operate at x16 or at x8 speeds. Both slots only operate at x8 when two video cards are installed, and the board is configured for SLI operation.

Your system is running right. Everything there shows up correctly.
 
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