Running video card on slower PCIe slot?

[wpcoe]

(I posted this question on in the Memory & Storage section, and didn't get any nibbles, so I thought I'd try here where the video experts hang out.)

On my P55 mobo, I have four PCIe slots:

PCIe 2.0:
one x16 slot

PCIe 1.0:
one x4 slot
two x1 slots

To keep this story short: Will my ATI Radeon HD 4670 video card operate in the PCIe 1.0 x4 slot, keeping the PCIe 2.0 x16 slot open?

If so, will I notice a difference in day-to-day computing? I don't play computer games, just basic word processing, internet browsing, and occasional Photoshop.

 

[Agenesis]

A 480 running at x4 has negligible impact when compared to x16. I'm sure your 4670 will be fine.

 

[toyota]

its just a pci-e 16x slot that runs at 4x speed so for your needs its fine. what I don't understand is why does only the regular 16x slot conform to the 2.0 standards?

 

[wpcoe]

As I understand it, the PCIe 1.0 slots are on a bus to the Intel P55 Express Chipset, and the PCIe 2.0 is on a bus directly to the CPU.

It's a bit confusing about the chipset PCIe lanes. According to an Anandtech article on the P55 chipset: "The PCI Express lanes are version 2.0 but Intel decided to limit their speed to PCIe 1.x specs at 2.5GT/s."

So, I guess technically all my PCIe slots are 2.0, but functionally the ones via the chipset are 1.0?

 

[wpcoe]

A 480 running at x4 has negligible impact when compared to x16. I'm sure your 4670 will be fine.

That chart is comparing PCIe 2.0 x16 vs PCIe 2.0 x4. Is it significant that in my x4 slot, it would be running at PCIe 1.x speed?

I'm mainly glad to know that my card would function in the PCIe 1 x4 slot.

I want to put a PCIe 1x card with SATA-3 (6 Gb/s) ports in a PCIe 2 slot, and the only one I've got is the 16x slot.

 

[Concillian]

That chart is comparing PCIe 2.0 x16 vs PCIe 2.0 x4. Is it significant that in my x4 slot, it would be running at PCIe 1.x speed?

I'm mainly glad to know that my card would function in the PCIe 1 x4 slot.

I want to put a PCIe 1x card with SATA-3 (6 Gb/s) ports in a PCIe 2 slot, and the only one I've got is the 16x slot.

It should function, but you would have to cut out the back of the slot. Otherwise it won't fit into the slot.

Found a log of someone doing it: http://thebsdbox.co.uk/?p=21

And here's one showing a different type of surgery to a PCIe slot: http://tkdan.com/SC420/
just stuff I found on google... point is you need to remove the back of the PCIe slot so the card can sit down in the slot.

 

[wpcoe]

Probably because the motherboard was designed for Crossfire, the form factor of the 4x slot is identical to the 16x slot:

While I had the case open, I moved the video card to the 4x slot, and moved one PCI card since the video card overlapped into that PCI slot,. After booting Windows 7 and re-installing the ATI drivers, everything seems to be running normally.

My only concern is the closeness of the video card to my modem in the adjacent PCI slot. They seem mighty close to me, but I don't think the modem (which is rarely used) generates much heat, and the side of the card adjacent to it is a solid piece of plastic, with no venting.