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Gen 8 PCIe Gen 3 limitations?


TomP
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The article is not very clear.  My initial guess, based on experience, is the following:

 

The MicroServer Gen8 has PCI-e 2.0, which means that you can install a PCI-e 3 card but its capabilities, especially with regards to speed of data transfer, won't be used to full extent.  In other words, your PCI-e 3.1 USB card should be backwards compatible with a PCI-e 2.0 system.  It will use PCI-e 2.0 features and capabilities, but it will basically work.  I would do further research on this hypothesis before spending money or investing a lot of time.

Edited by ullbeking
Added sentence to clarify.
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2 hours ago, ullbeking said:

The article is not very clear.  My initial guess, based on experience, is the following:

 

The MicroServer Gen8 has PCI-e 2.0, which means that you can install a PCI-e 3 card but its capabilities, especially with regards to speed of data transfer, won't be used to full extent.  In other words, your PCI-e 3.1 USB card should be backwards compatible with a PCI-e 2.0 system.  It will use PCI-e 2.0 features and capabilities, but it will basically work.  I would do further research on this hypothesis before spending money or investing a lot of time.

The reason I posted is because the HPE spec says Xeon models ARE PCI Gen3 but Celeron models are 2.0...

https://h20195.www2.hpe.com/v2/GetPDF.aspx/c04123182.pdf

 

This conflicts with the earlier link I posted, so does anybody know the real spec?

 

 

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1 hour ago, schoondoggy said:

What PCIe 3.1 card are you considering using?

 

I handn't got that far, I just see a few on Amazon. Have you a view on a good choice?

 

Also are we clear that if I upgrade to Xeon, then PCIe gen 3 is supported as in the attached spec?

 

I had looked for an enclosure that supports USB 3.1 but have not yet seen any 2-bay or 4-bay enclosures, although there are single drive enclosures so I could attach 2 to a USB 3.1 card, but this does not seem a very elegant solution. Any thought would be welcome.

 

Thanks again for your patient help, it is much appreciated...TomP

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Quote

The reason I posted is because the HPE spec says Xeon models ARE PCI Gen3 but Celeron models are 2.0...

https://h20195.www2.hpe.com/v2/GetPDF.aspx/c04123182.pdf

 

This conflicts with the earlier link I posted, so does anybody know the real spec?

 

The original link you posted had the following.  I missed it until just now:

 

"PCI Express Gen 3 cards are not supported in the HP ProLiant MicroServer Gen8 because the PCI Express Gen 3 speed is processor dependent. Currently only the Intel E3-xxxx v2 Xeon processor can support the PCI Express Gen 3 speed [...]"

 

So I interpret this as two possibilities:

  • any MicroServer Gen8 with an E3-v2 CPU installed will support PCI-e 3; or
  • only those MicroServer Gen8 systems released after an E3-v2 CPU became an option, and if the CPU supports it, will the system support PCI-e 3.

It is my understanding that there were two major revisions of the MicroServer Gen8, the second one being that which supports the E3-v2 CPU.

 

Also, I would think that the following excerpt from your original link (just after the above excerpt), is outdated and was written when only the first revision Gen8's existed:

 

"[...] the Intel E3-xxxx v2 Xeon processor is not supported in the HP ProLiant MicroServer Gen8."

 

The question then, comes down to the following:

 

Does a "first revision" MicroServer Gen8 with an E3-v2 CPU installed support PCI-e 3?

 

A useful auxiliary question would be as follows:

 

How does one know which "revision" of the MicroServer Gen8 one has?

 

What do you think?  I have two Gen8's and will have a close look at them tomorrow if I get time.

 

Edited by ullbeking
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On 3/2/2020 at 3:49 AM, ullbeking said:

How does one know which "revision" of the MicroServer Gen8 one has?

That is the question. Actually, everyone tried and all mobos worked well with V2 Xeon processors. So there must be something that affects exactly PCIe lanes.

If any system supports V2 CPU and there are no threads regarding compatibility you are unable to check it ising CPU BIOS microcodes.

 

I found out my E3-1260 is 2 times chepear to compare the pricing now and the time I bought it. V2 versions are also cheaper so I am considering CPU upgrade after I change RAM 8 ti 16Gb to let it run at hicher clock and P222 is also PCIe3 so it can give some HDD perfomance increase...

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