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How To Fix The PCI Express x1 Bug
The reason why I wrote this article is simply because I have seen many whom had their motherboard's PCI-Express bus width stuck at x1 while overclocking. This is especially seen on the ASUS P5B series. So today, we are going to find out what will work and what won't, as well as their impact on gaming and HD video playback.
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Motherboards that might be affected include :
- ASUS P5B
- ASUS P5B-E Plus
- ASUS P5B Deluxe/WiFi
- Gigabyte P35C-DS3R
- Gigabyte P35-DS3L
Graphics cards that might be affected include :
- ATI Radeon X1950 Pro
- ATI Radeon X1950 XT
- NVIDIA GeForce 8800 GT
Solutions that do NOT work :
- Setting the PCIE Bus Frequency to 96 MHz
- Setting the PCIE Bus Frequency to 101 MHz
- PCI Synchronization Mode to 33.33 MHz
- Updating the BIOS
Solutions that work :
- Disable "PEG Force X1".
- Set the NB Vcore to 1.45 v or below.
- Overclock or underclock the PCI Express reference clock (up to 15 MHz either way). More details here - PCI-E Reference Clock.
- New! Set PCI Synchronization Mode to Auto. This is an important step.
- New! Set PEG Link Mode to Normal (instead of Auto).
Many thanks to carambazi for his feedback, and congratulations on beating the PCI Express x1 bug!
How To Check If You Are Affected
Checking if you are affected is simple. Just use any system information utility, like CPU-Z or GPU-Z to check the PCI Express operating mode. Here are examples of CPU-Z and GPU-Z results for motherboards affected by the bug, and those not affected by the bug.
PCI Express x1 (Affected by the bug) |
PCI Express x16 (Not affected by the bug) |
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| In this motherboard, GPU-Z reported that the Bus Interface was PCI-E 2.0 x16 @ x1. Similarly, CPU-Z reported that while the Max. Supported was x16, the actual Link Width was only x1. | In this motherboard, the Bus Interface was PCI-E 2.0 x16 @ x16. Similarly, CPU-Z reported that the actual Link Width was the full x16. |
For those who are wondering just what kinda of impact does running at PCI Express x1 have on the performance of the system, take a look at the results in the following pages.
