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USB channels on ultra-d

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Hey guys..

Im having a problem with my stability and thing I have it narrowed down.

Whenever I have extended periods of high download rates (USB wifi) and at the same time use my tv tuner (USB). My computer freezes and I am forced to restart. It only happens when both devices are under heavy use.


I think its coming down to current draw through the USB bus. Both get really hot so I think they must be using alot of juice.. I believe that the USb can provide up to 500mah? I may be wrong..


I have heard that the USB connections on the MOBO that you would use for front panel or those extentions for the rear PCI slots are on a different channel than the intergrated ones on the back of the MOBO.

If so I could seperate the 2 devices and regain stability?

Can anyone confirm this?


thankx for any advice..

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All usb ports are still supported through the nVidia NF4 Ultra chipset though. If my memory serves me correctly, on my Ultra-D there are two different headers for the onboard USB.


Since your data is streaming on the USB bus the data is being transferred isochronous mode (i.e. real time with no error correction).


There is a possibility that you are exceeding the 480 Mbps of USB bandwidth that is available. When devices are enumerated, the host is keeping track of the bandwidth all of the isochronous and interrupt devices are requesting. They can freely use up to 90 percent of the 480 Mbps of bandwidth that is available. However, after 90 percent is used up, the host begins to deny access to new isochronous or interrupt devices. The remaining 10% of your USB bandwidth is reserved for control packets and bulk packets.


So I think that narrows your problem down to one of two things;


The first one you already pointed out - current draw from the USB devices exceeding the capability of the motherboard, usb controller and NF4 ultra chipset.


Secondly, by using both devices at the same time you are exceeding the available bandwidth of the usb bus thereby causing system crashes or hangs.


IMHO, it won't hurt to try the experiment you've proposed. But I don't know whether it will solve your problem or not. Thats something you'll have to tell us.

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Thats a good point you have there.

Im going to try using the front panel usb's to see if there is a difference. I also have a PCI USB card. So the PCI slot would be powering/transfering the data..

Hopefully something will work.

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