Gigabyte P55-UD6: Help with single graphics setup

My guess is that you've run into a lane limit of some sort; the PCIe channels for 1156 platforms are on the CPU, limited in number, and 'handed out' by the P55 - just to clarify, before I start digging, is that a P55, or a P55A?

It's the original P55, without USB 3.0 or SATA 6 GB support.

Well, that's good - I know for a fact that both USB3 and SATA3 'suck-up' lanes (if enabled) - I'll look see if there's an adjustment you can make... Back in a bit...

Dude! That was more information in one post than the @!%! Gigabyte so-called "Tech Support" has been able to muster in nearly two weeks!

(I feel obliged to pass this on, if only for the humor value.):

I wrote to them and asked this same exact question. I gave them the PCI and PCI-E card layout exactly as I did above, which, BTW, uses the slot numbering out of their own user manual. Both GPU-Z and the ATI Catalyst are reporting the card is running PCI-E Gen 1.1 x8. I also made it clear that ALL of my drivers are up to date.

The first reply was "How do you know it's running x8?" So I told them again. The second reply was "If you have a card in the x8 slot, it will slow the first slot to x8" So I told them AGAIN that that slot is empty. The third reply was, "Is the graphics driver up to date?" and "Did you update the graphics card BIOS?" And, finally, "Swap out the graphics card." THAT'S IT! And this took a week and a half! I understand it was the holiday week, which is why I didn't begrudge the time it took. However, this is the level of response I've come to expect from Gigabyte's Tech Support. They are utterly useless!

Anyway, I'll try your suggestions! Thanks! Pulling the CPU will have to be a last resort, given that that will essentially involve me taking a good portion of my system apart.

I do have 5 HDD and two Blu-rays in the tower. The two system HDD attached to the PCH are RAID 1 mirrors. The Blu-rays are also attached to the PCH. The next two HDD are on the JMicron controller, also as RAID 1. The last HDD is external, connected to the first eSATA port running in AHCI mode.

I'd only thought of the slots as being involved here, not the other resources on the board itself. Thanks for clearing that up!

So could you please confirm my understanding of what that P55 spec says? According to the Device Manager, I have four P55 PCI-E root ports. Are the four PCI-E ports mentioned in the spec the three x1 slots (counting the x4 as x1) plus the eSATA ports? Which is why, if you set the x4 slot to actually USE all four lanes, you lose the other two x1 AND the eSATA ports?

BTW, my root ports are 1, 4, 5, and 7. So it seems that any of those can give up their bandwidth to make a single x4.

I never understood why I also have one "Intel Processor PCI Express Root Port"! THAT'S the beauty on the Lynnfield CPU, isn't it? (And that's the one giving me a problem.)

You have just singlehandedly increased my understanding of this CPU/Chipset by like a factor of 100!  

Anyway, I'll try your suggestions and report back!

Again, I really can't thank you enough! Now I can approach this with a lot more understanding of how my system is interconnected.

-geo

You have a add on card in a pcie-4 slot. Is that correct ?
I believe you are hitting a limitation of the cpu/chipset.
You have 16 pcie lanes, total. Thats it.
The way the logic switch works, is if you have a card in the main slot alone 16 lanes.
Cards 1 and 2 , the logic switch goes 8x 8x,, (we all know that....)
Cards in 3 pcie slots 8x 4x 4x = 16 lanes
But having a card in the 4x slot creates a similar situation, the switch again
goes 8x, 4x, 4x,
its sort of all or nothing and in slot 1, but it can give you 8
lanes in your primary pci-e and then two more slots dividing the remaining 8.
Take out the card in the bottom slot and it should give you the 16x

Nah, notty - you've got it wrong; like I said, there are sixteen CPU-sourced lanes (which service the first two graphics card slots - you want your fastest, most tightly-coupled 'blasters' on the GPU, as it's the major bandwidth hog in a modern system, especially if you're using something like the ATI Avivo codec for your transcoding tasks, to take direct advantage of the GPU's specialty, video encoding...), then, everything else on the system that's hooked up, one way or another, to PCIe gets what's left over, sourced from the P55 itself... What we can't figure out is why, as you have said, when the CPU's lanes are servicing one GPU (again, it's either 1x16, or 2x8 - no 1x8, 1x4, + 1x4), it's 'kicking down' to x8 for a single card; although I suggested a few experiments with the other ports, they really shouldn't have anything to do with it - as, the CPU is servicing the first two slots, and only them, and doesn't have a real difficult decision to make as to whether there are one or two cards 'present and accounted for...'

Geok, I thought of a (probably irrelevant) question - do you happen to have a pair of displays hooked up to that card? It just occurred to me that my displays (four, two per lowly 3850 card) 'look' like four cards to the driver (though not to the hardware hook-up) - wonder if it might be the driver somehow 'misrepresenting itself' to the BIOS' OS start-up init routines... Have you maybe tried it under Ubuntu, or some other flavor of linux?

Try updating both your board's and graphics's BIOS to latest.
And, update the system drivers such as chipset & graphic.

Well guys, I am totally stumped. Bilbat, sorry for the delay in responding, but, no, I'm just using one monitor and one graphic card!

As you said, the x16 and x8 channels are on the CPU's on-die PCI-E controller. As the x8 slot is empty, I should get all 16 lanes, but I'm NOT!

Oh, and guys, for the love of god, don't ever bother with Gigabyte's "technical" support. They're response is ALWAYS either, "It's someone else's problem," or "Sorry, can't help. Goodbye." I've NEVER, in my 20 years as a NASA system administrator, run into a support staff that is less willing to lift a finger to help their customers, and that INCLUDES all of the government agencies I've had to deal with! In the five or six years that I've been using Gigabyte motherboards, they have never ONCE answered one of my questions.

Please do let me share this latest, classic example! As you probably know, if you're using Gigabyte motherboards, it's common for them to block the first x1 slot with a heatsink. Well, I wanted to know, on the P55-UD6, what's the length from the edge of the motherboard to the heatsink. I forgot to measure it before I built my system, and it seems to me even shorter than the standard Gigabyte fare. They've been unable to answer my question! Their first reply was, "That depends." Given that all I'm asking for is a fixed measurement, set in stone by their engineers when the board was designed, it does, in fact, not DEPEND at all! I've tried every way I can possibly think of to rephrase the question, but they are literally incapable of answering me! This is the standard caliber of support that Gigabyte provides its customers.

Anyway, back to the issue at hand. I'm at the point of giving up. I've tried everything I can think of, but two. All of my drivers and firmware is up to date. I even applied the latest beta BIOS to the board, but it changed nothing. Just for kicks, I did remove the board in the x4 slot, although Bilbat already explained why that shouldn't affect this whatsoever, and, indeed, it did nothing.

In fact, I've actually added a board. In addition to the USB/Firewire adapter in the x4 slot, I just installed a USB 3.0 card in that first x1 slot! (Hence the length question to Gigabyte, which did me no good.) Of course, that first x1 slot in on the chipset, the same as the x4 slot, so it hasn't made a difference, not that ADDING a card would help!

The only things I haven't tried are Bilbat's suggestion of taking out the CPU and checking the mobo pins to make sure that they're contacting the 1156 pads correctly. That will be my very last test, given how difficult it will be for me to take off my CPU cooler.

I also haven't swapped out the graphics card. I've misplaced my DVI to HDMI adapter that I was using with my old HD 3870, and I need it to plug my HDMI cable into that card. As my current card has an HDMI port, I'm not using any adapters right now. I'll probably find it in the next couple of days and then try my old board. Seriously, I don't WANT the old board to run at x16, as that would mean that there's a problem with my new board!  

That seems to be all I can try. To be honest, I'm at the point of deciding that I've spent too much time on this already. The display IS working just fine. I'm able to play Blu-rays perfectly, so, obviously, x8 throughput is easily enough.

Thanks again guys!

-geo

Hi,

I just noticed that this thread had been marked [SOLVED]. In fact, I'm no closer to figuring this out than I was when I first noticed the problem!

Despite all of the terrific, insightful feedback I received from forum members, I've yet to find an actual solution. I just said I was giving up, not that I'd fixed the problem.

In fact, the only reason I'm challenging this [SOLVED] tag is because I don't want someone who might have a similar problem seeing this and thinking, (incorrectly), that they'll be able to find the solution here.

Thanks!

-geo