Biostar PCI express 3.0 x16 help

[trenter_1984]

I have a biostar TZ77XE3 motherboard with two PCI express 3.0 x16 slots. I have been using my gtx 670 in the PCI express 1 slot with no problems, but recently had to move my card to the second gen 3 x16 PCI express slot after installing a cpu cooler. The problem is that my card shows as running gen 3 8x in gpuz but gen 2 8x in my bios and whenever i change the slot to gen 3 and save it doesn't change anything at all. I know i'm probably not losing any real performance but my motherboard is advertised as having two PCI express 3.0 x16 slots and I want to know if maybe i'm missing something. Also I tried correcting this with the original bios for this board and the newest bios I just flashed today with no luck.


Main components

biostar TZ77XE3
i5 3570k 3.4ghz
evga gtx 670 ftw

 

[TheBigTroll]

try clearing the CMOS first. the card should work either way

 

[ko888]

The Intel Core i5-3570K Processor has a maximum of 16 PCI Express Graphics lanes.

The BIOSTAR TZ77XE3 motherboard's PEX16_1 slot has all 16 lanes wired to the motherboard so BIOSTAR states that you should use this slot if you want your graphics card to utilize all 16 PCI Express lanes. When using more than one discrete graphics card in the system the number of usable PCI Express lanes is reduced to 8 (i.e. 8 lanes per discrete graphics card in 2-way CrossFire/SLI).

The PEX16_2 slot only has 8 lanes wired to the motherboard so it is physically impossible for this slot to use 16 PCI Express Graphics lanes. Since this is the slot you are using for your single discrete EVGA GTX 670 FTW this is why you are only seeing the graphics card's PCI Express bus interface running @ x8 (i.e. only using 8 lanes). No amount of BIOS flashing will ever change a physical limitation.

 

[TheBigTroll]

yes but it states that its runing at gen 2 8x not gen 3 8x

 

[trenter_1984]

You are correct but I didn't realize the physical limitation of the board either. My goal was to get it running at 16x speeds but now that I know it's impossible I would like to figure out why its only running gen 2 now. I have power saving features disabled in the bios so the board should be running gen 3 speeds at all times instead of being locked to gen 2 speeds. Thanks for your help.

 

[ko888]

Changing the PEX16_2 – Gen X BIOS setting to Gen3 will not force the graphics card to operate in PCI-E 3.0 mode. That BIOS setting only sets the maximum PCI-E generation that the graphics card will be allowed to run at. I would see it as a PCI-E Generation Limiter.

If you were to set it to Gen1 you should notice that the card won't operate at any higher than PCI-E 1.0.

You said GPU-Z was reporting PCI-E 3.0 x16 @ x8 3.0? If this is true then I would trust this over what your BIOS is showing.

 

[DJDeCiBeL]

I'm having issues understanding why the HSF is keeping you from being able to use the first slot.

Looking at the pics, I can't imagine any cooler that would block that slot (some might come close to the PCB of the GPU, but it shouldn't be unusable, in any case).

 

[TheBigTroll]

biostar likes to put their x16 slots as high as possible (never recommended biostar boards for their poor layouts). in theory the card can still work fine.

 

[trenter_1984]

I'm having issues understanding why the HSF is keeping you from being able to use the first slot.

Looking at the pics, I can't imagine any cooler that would block that slot (some might come close to the PCB of the GPU, but it shouldn't be unusable, in any case).

I have a thermaltake frio and it's quite large, also bigtroll is right as the slot is pretty high up on the board. I could probably remove the backplate from my 670 and fit it but it would certainly be touching the cooler. Can't even get it in the pci slot with the backplate on though.

 

[trenter_1984]

Changing the PEX16_2 – Gen X BIOS setting to Gen3 will not force the graphics card to operate in PCI-E 3.0 mode. That BIOS setting only sets the maximum PCI-E generation that the graphics card will be allowed to run at. I would see it as a PCI-E Generation Limiter.

If you were to set it to Gen1 you should notice that the card won't operate at any higher than PCI-E 1.0.

You said GPU-Z was reporting PCI-E 3.0 x16 @ x8 3.0? If this is true then I would trust this over what your BIOS is showing.

Yeah I just didn't understand why the bios and the system info in the nvidia control panel said pci 8x gen 2 but I think under load it does resort to gen 3. thanks for your help.

 

[trenter_1984]

Best answer selected by trenter_1984.