HP Compaq DC7900 SFF - No BIOS Support for USB Keyboard/Mouse

[jzat]

I recently purchased an off lease vintage 2009 DC7900 running Windows-7 Home Premium. It has motherboard connectors and BIOS support for a PS2 keyboard and mouse. It also has motherboard support for USB but apparently BIOS doesn't support a USB keyboard and mouse. Is there a BIOS update that adds support for USB keyboard and mouse?

Thanks

[Paul_Tikkanen]

Hi:

Something isn't right.

I have a dc7800, 8000 Elite and 8200 Elite CMT, and they can use both types of input devices (USB or PS2) with no problem.

If you have a PS/2 keyboard go into the BIOS and set it to its defaults.

The previous company may have configured the BIOS to disable the usb ports in the security menu.

If you don't have a PS/2 keyboard, shut down the PC, unplug it, disconnect everything hooked up to it (keyboard, mouse monitor, etc.), and press and hold the little yellow Clear CMOS button for around 15 seconds, and then hook everything back up.

That will reset the BIOS to its defaults and the PC will relearn all of the hardware.

You will need to go into the BIOS and set the date, time and change any of the settings you may want to have different than the defaults.

[jzat]

Thanks for the quick reply. I have a PS/2 keyboard so I just went in to BIOS setup and forced a return to factory settings. This unfortunately didn't solve the problem. The PS/2 keyboard works as expected; the USB keyboard is dead. When I get some more time, I'll try your second suggestion - clearing CMOS. I'll let you know if that works.

Thanks again.

[Paul_Tikkanen]

You're very welcome.

I hope that clearing the cmos fixes the issue, because you shouldn't be having any problems using a usb keyboard and/or mouse with a dc7900.

The dc7900 is the only model dc7xxx I have never owned, and all the rest of them from the dc7100, dc7600, dc7700 and dc7800 could use both types of input devices.

I have had some odd things happen to my desktops, and I found that clearing the cmos has always fixed the problems I was having (such as the PC not waking from sleep when you clicked on the mouse or pressed a key on the keyboard).

[jzat · Accepted solution]

Well, I've discovered what appears to be the problem. My USB keyboard and mouse are connected to a KVM switch which in turn connects to the HP PC. The KVM cable delivers both keyboard and mouse via a single USB connection. I connected a second USB keyboard directly to another USB port and as you said, the BIOS supported it. I then connected the USB keyboard and mouse to a simple USB hub and then to the HP PC and the BIOS didn't recognize the keyboard once again. It would appear that the issue is that the HP PC BIOS doesn't support keyboard connectivity behind a USB hub. I don't have any detailed knowledge of USB connectivity but would guess that there must be a protocol difference when I hub is in the middle - obviously the PC needs to address a specific device behind the hub.

In the end, I think I'm just stuck keeping a separate keyboard (PS/2 or USB) around for those times when I need to communicate to the BIOS.

I have another PC of the same vintage - a custom rig - and it handles the keyboard behind hub just fine. I wonder if all new PCs' BIOS handle this.

Thanks again for your responses - very helpful.

[Paul_Tikkanen]

You're very welcome.

I'm glad you figured it out.

I do not have anything like that on my PC's, nor do I have any USB hubs so I have never tried experimenting like that.

At least you know that there is nothing wrong with the PC's USB ports.