This concerns the Optiplex 3020 in a data-acquisition environment, Window 7 Prof. We have serious compatibility problems with a specific USB 2.0 device. All USB devices are routed through the xHCI controller by default. The 2.0 device, managed by the xHCI controller, is approximately 3 times slower (and sometimes exhibits hickups) comparing to the EHCI USB 2.0 controller. This has been confirmed by USBLyzer. Installing windows 7 which do not have the xHCI support yet, functions normally. Once the xHCI controller is installed: problems, and we cannot go back.
Googling on xHCI/EHCI switch will show a lot of problems on this. Users are despirately requesting for a BIOS option to switch back to EHCI mode for solving their problems. This is also the case in my situation.
The status quo is that we cannot use our 3020's (or any other PC using Intel's xHCI USB 3.0 contoller) in our plant and we have to use retired PC's using EHCI.
- Is there a possibility to go back to EHCI mode?
- Do you need a change in BIOS then? If so, we are waiting for it!
Kind regards, Martin
Use a powered USB 2.0 hub. There is no other way to force the slower speed.
A powered 2.0 hub does not solve the problem. All USB ports (even the real 2.0 ports) are routed through the xHCI controller. The xHCI slows down comparing to EHCI. So we do not need a lower speed, but higher speed for 2.0 devices. Again, let 2.0 devices be controlled by EHCI.
XHCI VS EHCI is like saying INTEL VS AMD its hardware so there would not be a switch for this.
PCI based cards with NEC Chipset: NEC720102 4x Ports Adaptor includes 3x External + 1x Internal Ports are USB 2.0 EHCI and USB 1.1 OHCI compliant. Enhanced Host Controller Interface EHCI is a standard based on USB 2.0
USB 3 based PCI-E with NEC/RENESAS USB3 Controller (uPD720201 & uPD720202) is the only other thing that you can try.
You MUST ATTACH SATA POWER for it to work properly.
Many thanks SpeedStep for your suggestions.
The last one, with a extra PCI card is a good one. However we already tried one with a NEC chipset, but with same results unfortunately. Even when USB devices are connected to this card, the xHCI controller is used... These PCI cards are also "xHCI compliant"..... So it is a driver problem as well, I think.
Kind regards, Martin
Then you need to get a low profile PCI 2.3 USB 2.0 CARD with NEC chipset and then a PCI-E TO PCI interposer with power adapter. That would be the only way to bypass and clock down to USB 2 speed and use Native to windows drivers. This device bottlenecks the bus down to 32 bit 33mhz via PCI to PCI bridge which is why it needs power.
Thanks for your suggestions speedstep. But how far do I have to go to work around the xHCI ? In the meantime we installed win7-32bit on the 3020, with no default support of xHCI. And operates wel on EHCI. IMHO, it should be possible in BIOS to switch between EHCI and xHCI mode for proper backwards compatibility of 2.0 devices.
In the meantime, nothing's happened here. No relevant answer from Dell. No other suggestions. A proper deinstallation possibility of xHCI would be nice as well. Yes, it is possible of course to deinstall the xHCI, but it results in a total fallout of USB.
What can I do when I want to continue with the 3020 on Win7 64 bit? I have a FS USB device which has a compatibility problem with xHCI and I want to go back to EHCI.