PCI Express doesn't detect GPU

[Edutron]

Hello, and thanks for helping first time builders like me.

After following the Build Your Own PC guide on this website, I turned on the computer and it gave me 1 long, 2 short beeps (graphics card related problem). I have a Gigabyte GA-870A-UD3 motherboard and a Gigabyte Geforce GTX 460 graphics card. This is how things went:

The motherboard has two PCI Express slots where my card can fit. In the instructions, they are labeled as:
- PCI Express x16 Slot (PCIEX16)
- PCI Express x16 Slot (PCIEX4)

The first one doesn't detect my graphics card, while the second one works perfectly. According to what I've previously read, "Regarding PCI Express, if it fits, it works".

Some notes:

- On the non-working slot the card powers up nicely (the fans spin). In fact, I didn't make any change regarding cables when I switched from one slot to the other.
- In both slots I pushed the card inside as much as possible.
- I even changed the motherboard for another one of the same model, since the technician at the shop didn't find any explanation.
- The rest of the computer works nicely. I've already installed everything necessary while using the PCIEX4 slot.

[glc]

Contact Gigabyte support. I have no rational explanation either!

[Nikon]

that truely is an interesting problem. you even changed out mobos and had the problem recur, and it only works with the x4 slot.

check the card's contacts. make sure none of them have anything on them. my gigabyte card came with a sticker on the contacts that left sticky goo on the contacts, which i opted to clean off prior to attempting to use it.

[Edutron]

Thanks for your answers. I did both things and am now waiting for Gigabyte to contact me. There was no sticker goo neither in the card nor in the motherboard, although something picked my interest:

The PCIEX4, even though it was the same size as the other slot, had about half the number of contacts. Can it be that there is a problem in one of the graphics card contacts that are used on the non working port but not on the other? In other words, can the graphics card be responsible?

[Nikon]

thats what i was thinking, i didnt have a problem like yours, but i figured that may be a possible solution. examine all the pins on the card itself and see if any are damaged look burned or corroded. it is possible (and most likely) the problem is in the card itself rather than 2 mobos with the same problem. then again it is also possible it could be something as simple as an irq setting in bios. best wait for gigabyte to get back to you.

[Edutron]

Nothing caught my eye, neither in the contacts nor in the integrated circuits. I was careful when I held it, and quite paranoic about static discharges. If Gigabyte says the same as you, I will most likely take the card to the shop and ask them to run some tests.

I'll post again as soon as I get news or find a solution.

[glc]

Gigabyte will quite likely have you send the card in and give you a RMA number if you are past the exchange period with your vendor.

[Edutron]

Gigabyte contacted me and recommended me to run a test using only the basic components of a PC and booting in fail-safe BIOS settings, but the problem persisted.

Afterwards I took the graphics card to the shop. There, they ran a test on another mobo which gave a short beep error code on boot, but then strangely booted into Windows. Since we couldn't exactly find what was wrong, I ended up changing the video card to another model (Asus GTX 470) which runs fine.

Well, in the end we can consider it a graphics card malfunction. Anyway, thanks for your help. Now I finally have a full working computer.