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PCIe v3.0 x16 (8.0 Gb/s) @ x16 (2.5 Gb/s)
#1
I am running the latest hwinfo64 fully loaded (running gpu-z render test ) and I get the following:
PCIe v3.0 x16 (8.0 Gb/s) @ x16 (2.5 Gb/s).

Should the above be corrected to:
PCIe v3.0 x16 (8.0 GT/s) @ x16 (2.5 GT/s)?

Examples:
PCI-E v3.0 is capable 8GT/S or 16 GB/S (on 16 lanes)
PCI-E v 2.0 is capable 5GT/S or 8GB/S
PCI-E v 1.0 is capable 2.5GT/S or 4GB/S

I have a PCI-E 3.0 graphics card on a PCI-E 1.1 slot.

I should be getting 2.5 GT/S on my 16 lanes graphics card or 4GB/S but it reports that I am getting 2.5Gb/s.

Can someone correct me if I am wrong or agree with me if I am correct.???? Is it a typo mistake or something wrong with my motherboard and for an unknown reason it cannot reach 4 GB/S????

GPU-Z is a bit more general, and reports this as PCI-E 3.0 x16 @ x16 1.1. So according to GPU-Z it should be outputting 2.5GT/S which means 4GB/S. Thanks

If it is a typo mistake please add this for correction in a later release.

   
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#2
The 2.5 Gb/s speed mentioned is per-lane, so what it actually says is that the actual speed is "like PCIe 1.1". I believe this is the correct representation as per the PCI Express specification. Devices do not explicitly say whether they run as PCIe 3.x (which is the specification revision that actually supports speeds up-to 8 Gbps per lane).
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#3
Thanks for the reply.
Do you agree with the following: It says that for 1.0 is 250mb/s per lane or 4gb/s for 16 lanes. So you should correct to 2.5GT/s. GT is not GB.
gigatransfers per second (abbreviated GT/s) and Gigabytes per second (GB/S)

PCI Express
https://en.wikipedia.org/wiki/PCI_Express

In a ×16 (16-lane) slot[a]

1.0 8b/10b 2.5 GT/s 2 Gbit/s (250 MB/s) 32 Gbit/s (4 GB/s)
2.0 8b/10b 5 GT/s 4 Gbit/s (500 MB/s) 64 Gbit/s (8 GB/s)
3.0 128b/130b 8 GT/s 7.877 Gbit/s (984.6 MB/s) 126.031 Gbit/s (15.754 GB/s)
4.0 128b/130b 16 GT/s 15.754 Gbit/s (1969.2 MB/s) 252.062 Gbit/s (31.508 GB/s)
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#4
OK, I'll change the wording from Gb/s to GT/s.
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#5
(03-31-2016, 11:51 AM)Martin Wrote: OK, I'll change the wording from Gb/s to GT/s.

Excellent Thanks
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#6
Thank you too for spotting this. I haven't noticed this discrepancy earlier and the PCI Express specification confirmes that you're right.
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#7
(03-31-2016, 12:04 PM)Martin Wrote: Thank you too for spotting this. I haven't noticed this discrepancy earlier and the PCI Express specification confirmes that you're right.

You are welcome.
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#8
Cypriot

Your have Intel GM45 chipset and please, see document Intel®  4 Series Chipset Family Datasheet For the Intel®
82Q45, 82Q43, 82B43, 82G45, 82G43, 82G41 Graphics and Memory Controller Hub (GMCH) and the Intel®
82P45, 82P43 Memory Controller Hub (MCH)
(4-chipset-family-datasheet.pdf) page 32, chapter 1.2.4.1 PCI Express* Interface


Quote:The (G)MCH supports either two PCI Express* 8-lane (x8) ports or one PCI Express 16-
lane (x16) port. The (G)MCH contains one 16-lane (x16) PCI Express port intended for supporting up to
two external PCI Express graphics card in bifurcated mode, fully compliant to the PCI
Express Base Specification, Revision 2.0
.


PCIe x16 Gen 2 is hardware limit for this chipset, also GM45 chipset have equivalents graphics port as G45 and can't support PCIe Gen 3 specification, but some GPU can work on PCIe Gen 2 bus.
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