PCIe Slot Version?

mcgriffo · 12 Jul 2011 at 11:11

I have 2 PCIe slots on my Dell Optiplex 960 mobo. The x16 one which houses the graphics card is - I think - pretty much definitely PCIe 2.0. It's the smaller x1 slot I'm not sure about. The online documentation for tne mobo says it has PCIe 2.0/1.0A - but doesn't say one applies to one slot and the other to the other. So I thought maybe it was just saying that they were both 2.0 but backwards compatible with 1.0A.

PCWizard says they are both 2.0.

I have my doubts as I'm still getting USB 2.0 speeds from a USB 3.0 controller I have in the PCIe x 1 slot.

How can I tell for sure?

Marine-RX179 · 12 Jul 2011 at 11:18

mcgriffo said:
I have my doubts as I'm still getting USB 2.0 speeds from a USB 3.0 controller I have in the PCIe x 1 slot.

Just want to check...what device are your connecting to the USB3.0 interface card? Cause connecting a USB2.0 device to a USB3.0 port won't make the USB2.0 device any faster...

Hagar · 12 Jul 2011 at 11:27

I would also have said they are both 2.0 as it is the on board chipset that provides the version, the actual slots are the same through the versions. Do you have USB 3 peripherals as well as the USB 3 controller.

The PCIe 2.0 standard doubles the per-lane throughput from the PCIe 1.0 standard's 250 MB/s to 500 MB/s. This means a 32-lane PCI connector (x32) can support throughput up to 16 GB/s aggregate. The PCIe 2.0 standard uses a base clock speed of 5 GHz, while the first version operates at 2.5 GHz.

USB 3.0 has transmission speeds of up to 5 Gbit/s, which is 10 times faster than USB2.0 (480 Mbit/s).

This means that 5Gbits/sec = 625Mbytes/sec, a v2.0 x1 slot will carry 500Mbytes/sec, not quite USB 3 but better than USB 2 (480Mbits/sec or 60 MBytes/sec).

mcgriffo · 12 Jul 2011 at 11:58

I'm connecting a WD 2TB External HDD which purports to have USB 3.0 connectivity.

Once again, using PCWizard, it says my PCIe x 1 slot has a "link speed" of 2.5GB/S (and the PCIe version as 2.0). That sound right?

Surveyor · 12 Jul 2011 at 12:31

The link speed is probably 2.5Gb(its)/s which after overhead etc. are taken into account equates to around 200MB(ytes)/s.

This is PCI-E 1.0 speed but should still be plenty enough.

Is the HDD in a dock or enclosure which has a USB 3.0 connection?

When you say you get USB 2.0 speeds what are you actually getting?

mcgriffo · 12 Jul 2011 at 12:45

Halfway through copying a 4.99GB folder from the desktop to the External HDD and it is hovering around the 24MB/Second mark.

The HDD itself is a Western Digital "My Book" so it is all prehoused - and alleges to be "USB 3.0 ready"

mcgriffo · 12 Jul 2011 at 12:49

Actually, just tested the same file on a USB 2.0 to a different HDD and it is hovering at 34MB/Second!

So that would make my USB 3.0 even SLOWER!

Something can't be right......

Surveyor · 12 Jul 2011 at 13:24

Did you install the USB 3.0 drivers?

In device manager can you see USB 3.0 ports listed?

mcgriffo · 12 Jul 2011 at 13:36

Yup, drivers are installed.

And in Dev. Mgr under USB Controllers there are two entries for USB 3.0

"Host Controller"
"Root Hub"

Surveyor · 12 Jul 2011 at 13:54

I'm confused by this "USB 3.0 ready".

It's either USB 3.0 or it isn't.

I suggest you do a bit of Googling on the drive you have, and the USB cable you're using, to see if they actually are USB 3.0.

USB 3.0 cables are usually blue inside the connectors.

mcgriffo · 12 Jul 2011 at 14:20

The "Ready" bit was probably my poor terminolgy.

The HDD is called:

Western Digital My Book 3.0 - 2 TB USB 3.0 Desktop External Hard Drive

The cable came with it and has the USB 3.0 connection point