SteveRance
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Precision R5500 PCIe cards being Back-Powered From any Display Device plugged in.

I have been testing out the Precision R5500 as a suitable replacement for an HP Z800. I seem to have come across a hardware issue that makes the R5500 unuseable.

One of my PCIe cards (a DeckLink Extreme 3D) fails to initialize in the BIOS after a power down. The exact error is "Alert! Error Initializing PCI Express slot 6", I have tried other slots with the exact same error message (execpt for the slot number!)

Another one of my PCIe cards (a Fairlight Crystal Core Card) has a number of LED's on the PCB. What is disturbing is that when the system is powered down, the LED's on the Crystal Core card are still illuminated.

I pulled the 110v from both PSU's in the R5500, let the system sit for 15 minutes ... and the LED's are still light up.

It seems that the back voltage from my Dell 2408 monitor (or any other monitor I have tried) is supplying power back thru the power supply lines and keeping all the PCIe cards in the R5500 alive. I have tried different graphics cards with DVI and Display Port with the same result. As soon as I unplug the DVI or Display Port cable the lights on the Crystal Core card go out. Once the lights go out I can then then power up the system, the DeckLink card then initializes correctly and the system starts as normal.

I have not had this problem with any other PC tested recently.

So to recap, it looks like the two risers in the R5500 are allowing power from a DVI or Display port attached monitor to supply enough power back into the system to prevent some PCIe cards from powering all the way down, the result of this is that the PCIe cards do not go through a power on reset as cards are being kept alive by the Monitors. So far, unplugging the monitor has had a 100% success rate enabling the system to start up as it should.

I have tried both disabling and enabling the "Low Power Mode" in the BIOS with no differance.

Does anyone have any ideas? If not how can I escalate this issue to the correct team as this seems at first glance to be a major issue?

As a side note, we sell between 50-100 systems a month and until this is resolved the HP Z800 will continue to be our prefferred Work-Station.

 

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Re: Precision R5500 PCIe cards being Back-Powered From any Display Device plugged in.

Hi SteveRance,

You should contact Dell sales support for help with this question.

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