Optiplex 9020 MT: Dedicated GPU only seen at x4

Question

Hello all, I've bought for cheap a Dell Optiplex 9020 Mini-Tower with an i5 4570, 16 gb of RAM, 500 gb HDD. I've then added a Samsung 850 EVO 500 gb SSD. Windows 10 Pro BTW... The problem: I've bought the cheapest GPU to upgrade from the integrated HD4600. It is an ASUS GT 710 silent and it is recognized only at PCIe 2.0 x4 even if it is in the blue slot. I've returned a GT 1030 thinking it was bad as it had the same behavior.  GPU-Z reports link width as x8 but max supported x4 even if I stress test the GPU (GPU-Z own render test, any benchmark or GPU stress test). I'm on latest BIOS revision dated february 27. So far, no BIOS or Windows settings did anything: - Removed battery, cleared CMOS shorting the pins and loaded defaults; - Disabled C-States or ASPM; - Disabled PCIe power management in Windows; - Running with bare minimum in BIOS: only one SATA port enabled, disabled all USB 2.0 and 3.0 except two ports for mouse and keyboard. For the record, I've tried three other old GPU's: a 8400 gs and a GT 210: not even recognized in the blue main slot, had to put them in the black slot. Too old? A Radeon HD6450: recognized in the blue slot but alas, only max at x4 too.   Is this: 1- By design? 2- PSU too weak (290w) throttling down the PCIe link? 3- Defective PCIe slot (cleaned with compressed air and a folded sheet of paper)?   Thanks for any ideas or insight,   Patrice

Patrice B · Accepted Answer

Solved...

I removed the CPU from the Optiplex and put it in a spare Gigabyte board (Z97) I have: same symptoms, no full x16 on the first PCIe slot. Conclusion: the CPU is malfunctioning, having only one x4 lane instead of 16.

Noticed when removing that the left corner (where is the little arrow) is slightly bent, so probably some contacts are bad.

Exchanged it for another Optiplex 9020 and, this time, full x16 (meaning my x8 card is seen as x8).

No wonder that some old x16 1.1 cards weren't seen at all on the main GPU slot!

Patrice B · Answer

Same GPU-Z results (link width x8 max supported x4) when I put it in the black slot. Isn't this slot supposed to be wired x4 only? For the record, Cinebench gives 35 fps, which seems to be ok for this kind of low end GPU...

???

elpro999dell · Answer

It's probably something with the motherboard as you said it does the same thing with other cards.

Patrice B · Answer

Thanks,

What bugs me is that the card looks to be functioning as it should, I mean Open CL (Cinebench) is normal. I looked at a Cinebench benchmark of GT 710 on the internet and my results are what they should be. I'm beginning to think that maybe it's only aesthetics...

Will try to downgrade for an older BIOS and see what it does...

Patrice B · Answer

Cleaned again PCIe blue slot, gone back to older BIOS versions, reseated GPU and RAM, loaded defaults...

Always stuck at PCIe 2.0 x4. Performance is the same on the black slot (Cinebench results are identical).

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