So I recently got a new rig together – first build, 3080 Ti (FE)/12700K, long time in the making/parts search stage, big upgrade from the old 2013-ish workstation laptop I’d been gaming on.

When I installed the GPU, I naturally put it in the top PCIE slot like I’d read everywhere. The latch clicked but it didn’t really “feel” right and the fingers on the GPU didn’t really look inserted into the slot (first clue). The PCIE brackets on the case and GPU didn’t line up either and the case thumbscrews wouldn’t screw in (second clue). I knew it needed to be screwed in though so I grabbed some longer CPU cooler mounting screws I hadn’t used earlier that happened to fit and screwed it in with those. It booted up, so I assumed this was OK.

It benched subpar but not horribly so. Timespy Graphics was about 17500 – underperforming but within the range of believability. Port royal was low – about 10700. That bugged me so I skimmed GPU-Z; recognized the GPU was a 3080 Ti, great. Number of shader cores and memory bandwidth on-point, great. I looked at the PCIE line and saw that it reported the GPU supporting PCIE x16 4.0, but since I was skimming I didn’t read/decipher further than that and assumed since it was in the top slot I was good. I ran Furmark with MSI afterburner to make sure it was running at a good frequency/memory speed/drawing 350 watts of power – all good. I tried reseating it and double checked to make sure the power cables weren’t “daisy chained” and it was actually connected to two ports on the PSU – all good there and nothing changed.

I chalked it up to luck but the game performance was clearly lacking – Cyberpunk wouldn’t run at a steady 60 fps on ultra no matter what I did (even at standard 1440p rather than my monitor’s native 3440x1440 with DLSS performance). Neither would RDR2 or Horizon Zero dawn. Shadow of the Tomb Raider struggled with ray tracing turned on regardless of DLSS settings. Trying to turn the settings from ultra to high or medium and play at high frame rates was a lost cause – almost like there was a “cap” I couldn’t see that varied from game to game. After about a week, I decided to reseat the GPU again (or at least try). It still wouldn’t line up and I pushed it in until I was worried about breaking something – no difference in performance either. After asking around in a tech-oriented discord group I frequent and coming up empty-handed for ideas, I figured I’d have to be happy with it.

Then one night I was poking around in 3DMark and decided to run the PCIE benchmark just to see what it was like; a slideshow came up and it reported 1.63 GB/s of bandwidth. That wasn’t right. I double checked GPU-Z and it was running at PCIEx1 4.0. That definitely wasn’t right. I gave up on reseating it in the top slot but decided to insert the GPU into the bottom slot running at PCIE x4 3.0. This time, it seated properly and the PCIE brackets lines up -- I was able to screw it in with the included case thumbscrews.

While this wasn’t “ideal”, it doubled the available bandwidth and games and benchmarks shot up as well – port royal was now getting about 11900. Timespy graphics saw a boost to over 18000. Horizon Zero dawn, Red Dead Redemption 2, and Shadow of the tomb Raider with ray tracing were now running at a stable 60 fps without DLSS. Hitman 3 dartmoor benchmark and Horizon Zero dawn on high settings still lacked compared with online benchmarks, but by maybe 10 – 20% rather than 30 – 40%; definitely a big difference and one worth making the switch for.

If you’ve read this far, thanks and I hope you or someone you know can benefit from this at some point; it was definitely a difficult issue to track down for me (albeit, I’m a first-time builder) but the results were worth the effort to fix it. As for my top PCIE slot I assume it's defective or broken but if anyone has any experience with this sort of issue feedback is welcome.

Hey Everyone,

I got a new computer and was running gpuz with the render test for my 3080, and I'm concerned, in all the videos I see, it's pretty staight bar, mine seem to be fluctuating up and down, should I be concerned? I'm a bit of a newbie with this?