GPU in X16 slot running on X4?
Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=2313
Printed Date: 23 Dec 2024 at 1:53am
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: GPU in X16 slot running on X4?
Posted By: paparazzo79
Subject: GPU in X16 slot running on X4?
Date Posted: 27 Mar 2016 at 4:12am
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I run GPU-Z and under Bus Interface I see this: PCI-E 3.0 x16 @x4 1.1 I own Asrock 990 FX Extreme 3 and I'm sure I put graphic card in X16 slot,it's in PCIE2 slot. But why is it running in X4 mode,and how to fix this? |
Replies:
Posted By: Xaltar
Date Posted: 27 Mar 2016 at 4:24am
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In GPUZ next to where the bus interface is listed there is a "?" click it and then click "Start Render Test". The Bus Interface should then change to the correct value. This is because the system lowers the bus interface when not under load for power saving. If it does not change then let us know. ------------- 
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Posted By: paparazzo79
Date Posted: 27 Mar 2016 at 4:35am
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It changed to x4 2.0. So what to do next,is that normal or not? |
Posted By: Xaltar
Date Posted: 27 Mar 2016 at 5:25am
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Do you have any other PCIe devices installed in the system? It should be PCIe 2.0 x16. I would try removing the graphics card and cleaning its contacts with some cotton and isopropyl alcohol. If you can, use a can of compressed air to blow out the slot from dust then make sure you seat the GPU properly in the slot and try again. -------------
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Posted By: paparazzo79
Date Posted: 27 Mar 2016 at 5:51am
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OK I will.Do I suffer some performance issue with x4 2.0 mode compared to x16? I don't have other devices installed. Nor I never ever removed graphics card from that slot since I bought the components,so I don't think it's dust/dirt problem. |
Posted By: Xaltar
Date Posted: 27 Mar 2016 at 6:39am
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Performance issues would depend on the GPU you are using. A GTX 780/R9 290 for example may suffer a performance hit but an R7 260/GTX 750 may not. The PCIe slots are rated as they are because of bandwidth. PCIe 2.0 x16 is what your GPU should be using but you are only getting x4 which means it is operating at a quarter of it's possible bandwidth. That isn't the whole story though, the speed you see is determined not only by the slot bandwidth but also by the speed of the device connected to it. If your GPU is mid to low end then PCIe x4 shouldn't be holding you back performance wise but if it is an upper mid range or faster GPU you will suffer more of a bottleneck the higher up the chain you go. Ultimately though PCIe 2.0 x4 would only bottleneck a high end GPU by at most 10fps in games. That is worst case scenario and would only really happen in titles where you are getting particularly high fps to begin with. If you have a game running at 30fps you may see 31fps or 32fps if you were not bottlenecked where a title running at 100fps may go up to 110fps if you had the full x16 bandwidth available to your GPU. Basically the bottleneck scales to the amount of throughput going through the slot to the CPU. -------------
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Posted By: paparazzo79
Date Posted: 27 Mar 2016 at 3:49pm
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I will unplug and plug the card,but before that clean the contacts on it. My card is Sapphire HD 7790 1 GB so I don't know if I suffered performance issues all the time. It was a midrange card back in the time when I bought it. |
Posted By: Xaltar
Date Posted: 27 Mar 2016 at 4:01pm
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You shouldn't see any noticeable performance loss on the HD 7790 so I wouldn't worry even if you are limited to x4 from a performance standpoint. It would be good if you can get it to run at x16 however as that is the speed it should be running at, the fact that it isn't means something is not working as it should. That said, if the system is working well and not showing any instability or other issues I wouldn't worry too much about it. -------------
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Posted By: paparazzo79
Date Posted: 27 Mar 2016 at 7:18pm
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Yep,I unplugged and plugged graphics card and now working as 2.0 x16,but I broke a little piece of plastic of slot,which keeps graphics card in place. Can I somehow take it off from other PCI express slot and plug back in on needed slot? |
Posted By: Xaltar
Date Posted: 27 Mar 2016 at 9:48pm
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You mean you broke the retention clip? If they are the same on both PCIe slots then yes, you could carefully remove the good clip from the other slot and attach it to the one you need it on. Just be very careful not to damage the board itself  -------------
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Posted By: paparazzo79
Date Posted: 28 Mar 2016 at 12:28am
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Yep retenntion clip.How do I remove it? |