Link Width problem

[Binary12]

Hi

I noticed that my PCIe ?Link width? is set to 4x rather than the maximum 16x (using CPU-Z). After reading the forum, I understand having your link width decreased like that is really bad and can (or will?) effect your GPU performance. My problem is that the only advice on how to fix it I could find was ?you can change it in the BIOS?, but I can?t find any such option. The only PCI related options I could find was to set an IRQ number (auto by default) and overclock options but nothing there mentioned link width or anything similar as far as I could see. I?m running the latest BIOS driver on a Gigabyte GA-EP35-DS4 motherboard and my GPU is a BFG Geforce 8800GTS 512Mb. Does anyone know what might be the reason for this and how I can solve it?

My system:
Gigabyte GA-EP35-DS4
Intel Core 2 Duo E8400 3,0Ghz
BFG Geforce 8800GTS 512Mb

The reason I checked to see my link width was because recently (after the latest patch) I have been experiencing low FPS problems in World of Warcraft, a problem now occurring for many players. Anyway, on the WoW forum there was a guy posting a screenshot from CPU-Z showing that he had link width set to 1x instead of 16x and the Blizzard support said this might be the reason for the FPS drop. The support guy referred to the motherboard manual on how to change it, but in my case it says nothing about this matter which leaves me clueless.

Another thing I noticed using CPU-Z was that my clock frequency at idle was at 2Ghz, instead of 3Ghz but went up to 3Ghz when I started a game or program, is that normal?


As always happy for any help you can give!

/B

 

[ViRGE]

IIRC that board has a 16x slot(blue) and a 4x slot(orange). Are you sure you have your video card in the blue slot?

 

[Binary12]

Well, as far as I know my motherboard has 2 PCIe 16x slots? I am currently away and can't check for sure but I do know that my graphic card is plugged into the second slot (the one furthest away from the processor if that helps). Could it be that this slot is not a 16x slot?

/B

[EDIT]
You are absolutely right! I checked the specifications on gigabytes page and it says:

2 x PCI Express x16 slots (The PCIE_16_1 slot supports x16; the PCIE_16_2 supports x4.)

But why call it a x16 slot if it only supports x4?
Anyway, I guess I'll change my card to the other slot asap but could this have caused the lower performance? It is a real odd issue that many people have experienced - New computers with dual-core processors and WinVista and suddenly a terrible decrease in FPS after the patch.

I'll move my card and see if this changes things to the better. Thank you alot for your help!

/B

 

[ViRGE]

It's called an x16 slot because physically it is x16, electrically it's only x4 however, if that makes any sense. The P35 chipset doesn't have enough PCIe lanes for 2 full x16 slots, but motherboard manufacturers still like to install the second x16 slot in place of a smaller PCIe slot so that users have the ability to install a second x16 card (primarily for Crossfire, although performance does suffer some).

And yes, having a card in the x4 slot instead of the x16 can hurt performance. It should be nothing dramatic, but it will keep you from maximizing your video card's performance due to starvation.

 

[Zap]

Originally posted by: Binary12
But why call it a x16 slot if it only supports x4?

The P35 chipset only supports one x16 slot. Your board has two physical x16 slots (as in can take a video card), but the second one is electrically an x4 slot because that's what the chipset supports. Because of the way PCIe cards work, a card can always (usually) work with fewer PCIe "lanes" albeit at reduced performance.

 

[Binary12]

Thank you both for your help! I will move my card and get back to you later about the result!

/B

[EDIT] I mentioned earlier that my clock frequency at idle was at 2Ghz, instead of 3Ghz but went up to 3Ghz whenever I stressed the processor a bit (running a game for example) is that normal?

 

[ViRGE]

Yep, that's SpeedStep in action. Your processor is downclocking itself and lowering its voltage when idle to save power.

 

[betasub]

^ ViRGE's response is correct. If you want to know more about this, please see the sticky post at the top of the CPU forum.