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7970 Low Bandwidth (8x)

Last response: in Systems
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February 5, 2013 11:35:12 PM

I'll try to resume as much as possible my situation:

- After an international relocation my Asus 7970 simply died - Strange symbols while power so I reclaimed a refund from the moving company.

- I acquired a brand new Sapphire 7970 Vapor to replace the faulty one, no big surprises everything works as expected...However when I checked the card details I see it is negotiating in 8x instead 16x

My previous asus was on 16x and the new one is connected on the same slot




Troubleshooting so far:
Mobo: Asus Rampage IV LGA2011
- Clear CMOS
- Configure settings from scratch - XMP (1866) with auto OC
- Upgrade to latest bios
- Change card to another x16 port
- Re-rechecked all cables, connectors etc.
- Cleaned slots
- tried another card 6970 in the same port and works on x16


I saw on several reviews of my video card that it is indeed pcie 3 x x16 so im really confused

What would you suggets?

Thanks

More about : 7970 low bandwidth

a c 136 B Homebuilt system
a b Ĉ ASUS
February 6, 2013 12:18:21 AM

Im not 100 % sure but I think the card is actually in x16 pci-e 2.0 which is what the card supports

and that is the same bandwidth as x8 pci-e 3.0
which is what your intel chipset mb supports
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a b B Homebuilt system
a b Ĉ ASUS
February 6, 2013 1:30:50 AM

When you do a render test does it change? (Click the blue question mark next to it)
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a b B Homebuilt system
a b Ĉ ASUS
February 6, 2013 1:59:44 AM

The 7970 is a PCIe 3.0 part. Odd that he says the 6970 showed PCIe 3.0 x16 as that is a PCIe 2.1 part. Perhaps he is only focusing on the 16x and ignoring the other. I'm not going to sit and read the manual for your board, but any chance you have another PCIe device plugged in somewhere and its dropping to x8 because of that? It's not a big deal to have it in x8 mode. Its not like your frame rates will double if goes back to x16. I would check to make sure the slot and card are clean and fully in, and read the manual in regards to what will make a x16 slot run at x8.
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a c 136 B Homebuilt system
a b Ĉ ASUS
February 6, 2013 2:21:43 AM

That was my next thought .

The pci-e x 16 slot will be paired with another slot for the second graphics card. If there is ANYTHING in that second x16 slot it has to cut the bandwidth of the graphics card in half .
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February 6, 2013 9:24:32 AM

k1114 said:
When you do a render test does it change? (Click the blue question mark next to it)


It changes from 8.1.1 to 8.3
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February 6, 2013 9:27:11 AM

4745454b said:
The 7970 is a PCIe 3.0 part. Odd that he says the 6970 showed PCIe 3.0 x16 as that is a PCIe 2.1 part. Perhaps he is only focusing on the 16x and ignoring the other. I'm not going to sit and read the manual for your board, but any chance you have another PCIe device plugged in somewhere and its dropping to x8 because of that? It's not a big deal to have it in x8 mode. Its not like your frame rates will double if goes back to x16. I would check to make sure the slot and card are clean and fully in, and read the manual in regards to what will make a x16 slot run at x8.


Indeed, when x6970 is shown as pci 2.1 x16, I tried another 7970 from a friend on the same port and is reported PCIe 3.0 x16

http://www.sapphiretech.com/presentation/product/?cid=1...
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a c 106 B Homebuilt system
a b Ĉ ASUS
February 6, 2013 9:39:10 AM

Wouldnt worry about it, Gen2 8x is more than enough for even the most powerful of cards, Gen3 8x is more than sufficient.
But I can understand that you want everything to work correctly.
I reckon that chances are you have another PCI card in a slot that uses the bandwidth of the slot your using.

According to the mobo specs, the top red PCI-e slot will always run at 16x regardless of the other slots, if you arent using that I suggest you move the card there.
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February 6, 2013 10:00:58 AM

manofchalk said:
Wouldnt worry about it, Gen2 8x is more than enough for even the most powerful of cards, Gen3 8x is more than sufficient.
But I can understand that you want everything to work correctly.
I reckon that chances are you have another PCI card in a slot that uses the bandwidth of the slot your using.

According to the mobo specs, the top red PCI-e slot will always run at 16x regardless of the other slots, if you arent using that I suggest you move the card there.



Yes I know but with 16x bandwidth improves @ least in +6gbps - I´ve it running on the top slot and i also tried in the secondary slot but same thing...

Could be a faulty card? http://www.sapphiretech.com/presentation/product/?cid=1...
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February 6, 2013 10:28:34 AM

The following statement in the video card brochure

PCI Express 3.0

PCI-Express 3.0 delivers double the bandwidth per lane of PCIe Gen 2 for faster GPU (GPU communication-up to 16GB/sec in each direction), maximizing the performance from your GPU when paired with the latest platforms.

what do you understand? is gen 2 8x?
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a c 106 B Homebuilt system
a b Ĉ ASUS
February 6, 2013 10:36:43 AM

1, 4, 8 and 16x refers to the number of physical lanes between the CPU and PCI slot, not necessarily bandwidth.
A Gen3 lane has twice the bandwidth of a Gen2 lane, so a Gen3 8x slot is equivalent in bandwidth to a Gen2 16x. Gen2 8x is enough for the most powerful of cards, so in all likelihood you could run a card from a Gen3 4x slot without issue.
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a b B Homebuilt system
a b Ĉ ASUS
February 6, 2013 12:19:18 PM

It's odd however that a friends card runs at PCIe 3.0 x16. As I understand it if the card is dirty it will work till where the dirt is. (or tape which is how this was tested.) You might want to pull your card and make sure the gold pins are clean. I wouldn't worry about the "missing" bandwidth. As I already stated even if you were at PCIe 3.0 x16 instead of x8 your scores won't change. Your frame rates will be 99% identical to what you get right now.
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