SammyVV
6 Indium

OptiPlex-790 and PCIe x16

Hiya

I am greatly confused with this. In the product specification is stated that on the motherboard there are a x16 PCIe and a x16 PCIe that is wired for x4. This much I understand, well at least as much that the other x16 PCIe entry is physically same size than the other, but has only 1/4 of its speed. What I don't understand is that the motherboard uses Intel Q65 Express Chipset that seemingly cannot support x16. How does this work? Chipset does not handle/provide all the PCIe lanes? If the x16 really exists, is it 2.0?

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SammyVV
6 Indium

RE: OptiPlex-790 and PCIe x16

Now I can actually answer to my own question. The x16 slot really exists and it is not provided by the chipset. However, this slot has a weird wattage restriction.

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8 Krypton

RE: OptiPlex-790 and PCIe x16

The wattage Restriction is based on the Power supply.

25W is max for Low profile Slots.  75W is based on a 305W power supply.


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SammyVV
6 Indium

RE: OptiPlex-790 and PCIe x16

Thanks for the answer! This would be a good news, however, are you completely sure about this? Is there any (software based) way to actually make sure / measure that the PCIex16 Slot (BLUE) can provide over 35 wattage, that is stated to be the max in the specification? Or is stating these "limits" common approach for Dell to make it easier for people to figure out what can be connected to the computer, without need of replacing the power supply?

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SammyVV
6 Indium

RE: OptiPlex-790 and PCIe x16

Did some more digging. At the spec it states: "voltage supported 3.3/12V". From wikipedia I found that the standard 75w forms from 3.3 V × 3 A + 12 V × 5.5 A. So assuming the A is same and PCIe standard is followed, it should provide than 35w. Does Dell follow standards?

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