1 Copper

Dell Optiplex 755 MT PCI-e Slot Problem

This will take a bit of explaining, so here goes...

I recently acquired a "new" refurbished Optiplex 755 Mini Tower, and thus far I have experienced no problems with the exception of one... the speed of the PCI-e slot.

According do the label on the board, it's a 2.0 x16 slot, and should accept cards up to x16. I've installed an EVGA GeForce GT 730 in to the PC and it's running great. The card is a PCI-e 2.0 x8 card.

However, every piece of software I've used to detect the speed that the card is running at all say the same thing... that it supports x8 but it's running at PCI-e 1.1 1x which is incorrect.


GPU-Z : 1.1 x8 @ x1.1 1

CPU-Z : Link Width: x1 / Max. Supported: x8

nVidia Inspector: 2.0 @ 1.1 x1

nVidia Control Panel : IRQ Not Used / Bus: PCI Express x8


Things I've tried:

- Updated BIOS to most current version

- Updated graphics card to most current version

- Reseated the graphics card

- Cleaned the PCI-e slot and graphics card pins

- Ran Dell SupportAssist test on graphics card and motherboard (passed)

- Ran Render Test from within GPU-Z

- Researched on the internet for weeks to no avail

As this is a Dell PC, the BIOS is somewhat minimal when it comes to overclocking and such, so I cannot change any aspects of the PCI-e slot whatsoever. I cannot find any software that could do it either, if it even exists.

I cannot RMA the card as I've modified the heatsink shroud to make it fit, and I cannot afford a replacement right now... should the card be faulty, which it shouldn't be because it was brand new.

I can afford a replacement motherboard if needed, but only if it's definitely at fault.

Does anyone with knowledge of the Optiplex, the motherboards they use, or PCI-e speeds have any suggestions as to what else I could try?

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2 Replies
7- Thorium

RE: Dell Optiplex 755 MT PCI-e Slot Problem

The bios and the bus are not designed to accept X4 or X8 cards.  So when it see's a card less than X16 it automatically sets it to X1.

You need a different 730 Card like this one.


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1 Copper

RE: Dell Optiplex 755 MT PCI-e Slot Problem

Wait... what? So it's not compatible with any other card except a x16? I honestly expected it to work with at least a x8...

But looking at nVidia Control Panel states the PCI Express to be running x8 mode, and CPU-Z states the maximum supported speed is x8. So although the speed (max) is being detected as x8 it still won't RUN at x8?

Does this have much of an impact on performance if it's running at true 1.1 x1 speeds?

Most of the cards I've just found that are x16 appear to be somewhat of a downgrade compared to my current card, which is this one -->


Also, any that DO seem compatible are all outside of the UK and cost far too much.

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