PCI Express Questions with Asus P8Z68-V_LX

X82 · 31 Oct 2015 at 09:03

Using my P8Z68-V_LX I have one ATI Graphics card in the main PCIEX16_1 slot. In the PCIEX1_1 slot I have my sound card and it all works great. I'm thinking of buying a USB 3 PCIE card and I am worried it won't work. Something to do with bandwidth. I worry that if I plug it in the PCIEX1_2 slot, the others will not work or lose "power".

The manual is just gibberish to me, I don't get it.

PCI Express x16_2 slot (Black) Bandwidth [2,0,1,1, x2...] Allows you to select the bandwidth of PCI Express x16_2. Configuration options: [Auto] [4,0,0,0 x4 mode] [2,0,1,1 x2 mode]

Will this card work? This is the card

The main issue I have, is when looking at my graphics card, it is blocking the only remaining free PCI-E X1 slot, typical. So would I suffer if I moved my graphics card to the other PCIE x16 slot?

stulid · 31 Oct 2015 at 09:10

Stick it into the long black slot (always wired for 4x) and it will work without altering any of the other slots.

X82 · 31 Oct 2015 at 09:30

Ah brilliant. Frees up a slot. That won't affect gaming being at 4x?

stulid · 31 Oct 2015 at 09:39

If your GFX card is in the blue long slot at the top, that is always 16X no matter what is happening around it.

The small print for that board says,

Note
*1: The PCIe x16_2 slot shares bandwidth with PCIe x1_1 slot, PCIe x1_2 slot.

So that is saying the black slot shares with the two small 1x slots.

That is perhaps why it is only 4X maximum.

X82 · 31 Oct 2015 at 09:42

Ah.
The issue is when in the blue slot, it takes over a PCIE x1 slot, which I need. But it would seem moving the graphics card to the black slot would free it up, from drop from 16x to 4x.

stulid · 31 Oct 2015 at 09:45

Dont move the gfx card for the sake of a USB card, thats rubbish.

As far as I can read, placing the USB card into the black one will work.

X82 · 31 Oct 2015 at 09:47

I know, tis bad form. I don't have the money for a new mobo. I got this card as a birthday present because the mobo built in USB 3 is broken and the remaining usbs act up times.

stulid · 31 Oct 2015 at 09:49

The USB card will work in the black slot.

Perhaps there's some confusion here and you think a 1X card must be in a 1X slot? when in fact you can stick it in a 4X/8X/16X slot.

Or in the case of this black slot, its physically 16X in length but only electrically wired at 4X (if you look inside you should see the contacts dont go all the way along.

X82 · 31 Oct 2015 at 16:35

Ah. What a fool I've been.
I've been using and in some cases, building PC's for nearly 15 years and I didn't know this!
It doesn't matter however. I plugged the device in, connected it to sata power, plugged in my external usb 3 HD and turned on the computer. Walked off to grab my cup from a shelf, walked back and smoke was billowing from the case. The wires connecting the card to a molex connector was glowing and smoking.

It also blew the HD external chassis (HD itself is working).

Stunned.
Returning. But at least I found out something new today.