AnsweredAssumed Answered

R7 350 2gb ddr5 from Sapphire, limited 8x bandwidth instead of 16x and slow boot

Question asked by vengefulpanda on Feb 19, 2017
Latest reply on Feb 21, 2017 by vengefulpanda

TLDR: Specifically, this newly installed card isn't achieving the full 16x bandwidth it is spec'd for even though it's in a PCIe 2.0 16x slot, and additionally, starting up the computer now takes an extra 30 seconds before post- the screens are just black for a while, no signal. Bootup and shutdown do function ok just slower, the card does more or less what it should, just in a kind of gimped way.


Here the full information about what is going on, in a step by step fashion relating what happened and how I've tried to fix it thus far. Thanks in advance for any help!


1. Issue appeared after upgrading system's graphic card from Radeon HD 6670 to Radeon R7 350. Motherboard is ASUS P5Q Pro, CPU Intel Quad Q6600 @2.4ghz. ALL EATX12v Power Cables (1x 8 Pin, 1x 24[?] Pin) are connected to MB and Ecosilent PSU is 750w. 8gb Gskill DDR2 Ram @800mhz. Display: Card is connected to 1x 1280x1024 NEC monitor VGA and 1x ASUS 1920x1080 monitor DVI. There is NO other card in any of the other PCIe 2.0 slots, and the other PCI 1.0 slots are empty as well


2. With the previous card (HD 6670), I confirmed that the PCI-E Bus Interface information was "PCIe x16 2.0@ x16 2.0" i.e. the full available bus bandwidth WAS being utilized and IS still utilized when I returned the old card to the system to test. I used Display Driver Uninstaller to clean uninstall catalyst drivers before physically switching the cards out. I replaced HD 6670 card with r7 350 card in THE SAME PCIe Slot on Motherboard - that (blue PCI-e 2.0 x16 slot) closest to the CPU, and the primary, the one which my Motherboard manual said to use if only one graphic card is installed. The slot is a PCIe 2.0 x16 slot. It is the exact same slot which the older HD 6670 had been plugged into. I then installed the newest stable Radeon Crimson drivers.


3. After the first time using the new card, I immediately noticed two changes to computer functionality (and slightly worse than expected gaming performance):

A. 30 Seconds extra now elapse after starting PC before Motherboard Logo first appears, and shutdown time is increased.

B. In AMD settings monitor (driver software), HWinfo64, and GPU-Z the following information about PCI-E Bus Interface is provided: "PCIe x16 3.0 @ x8 2.0" and "PCIe v3.0 x16 (8.0 GT/s) @ x8 (2.5 GT/s)". Basically, the card is being limited by something. In CPU-Z under "mainboard" I see the information "Graphic Interface: Link Width x8, Max Supported x16". The AMD Radeon Settings software simply says "Bus Type: PCI Express 3.0" and "Current Bus Settings: PCI Express 2.0 x8" but I CANNOT change the "x" value to 16 here OR in my motherboard's BIOS, as far as I know. I have spent a lot of time looking.


4. Attempts to fix both the startup issue and to realize full PCI-e bandwidth of card thus far completely unsuccessful. Card PCI-e Bus Bandwidth remains at x8 (not x16) under load, i.e. playing BF3 at ultra settings or running 3DMark Firestrike, etc. Checked power saving settings, PC power plan is High Performance and power saving is not enabled in the BIOS afaik. Updated Motherboard Bios to newest version today, still no fix. Re-installed new AND old cards to test (ultimately leaving NEW r7 350 installed in the PC) and safely uninstalled/re-installed drivers multiple times, with no fix.


Can anyone please help me figure out what to do about these two issues, the 1. long wait to boot and the 2. restricted PCIe bandwidth? Thank you!