Question RX 6600 Running at x4 PCIe 3.0 instead of x PCIe 4.0? [Help]

[MK_DEATHANGEL]

Hi Y'all,
As you can see. My RX 6600 Running at x4 PCIe 3.0 instead of x PCIe 4.0.

I am using Windows 10. Drivers are updated (to Dec 22).

Motherboard is B460M Mortar Wifi (MSI)
i5 10400F
2X16GB 2400Mhz Rams

I can confirm that I am using the first slot for RX6600 and there is no other card placed on the second X16 slot.

Help will be appreciated!

 

[volkgren]

Your 400 series motherboard is only PCIe 3.0, 500 series AMD boards are PCIe 4.0, 600 series are PCIe 5.0..

We currently do not notice much difference in GPU performance with PCIe 3.0, 4.0, or 5.0.

As far as it only running in x4 mode, that may be by design of the GPU. I'm not sure. Seems as though the RX 6600 is limited to x8 PCIe lanes.

I'm wondering if being in PCIe 3.0 limits it further to only x4 lanes.

Relevant video comparison:

 

[volkgren]

I just checked mine, yep I think so. My RX 6950 XT is running in PCIe 3.0 x8 on my X470 motherboard. Seems like I remember coming across that and comparing the performance difference and deciding to go ahead anyway. Not worth it to upgrade from PCIe 3.0 on the sole basis of gaining PCIe 4.0 or 5.0

In comparison, there's not much difference in performance.

 

[MK_DEATHANGEL]

Your 400 series motherboard is only PCIe 3.0, 500 series AMD boards are PCIe 4.0, 600 series are PCIe 5.0..

We currently do not notice much difference in GPU performance with PCIe 3.0, 4.0, or 5.0.

As far as it only running in x4 mode, that may be by design of the GPU. I'm not sure. Seems as though the RX 6600 is limited to x8 PCIe lanes.

I'm wondering if being in PCIe 3.0 limits it further to only x4 lanes.

Relevant video comparison:

Thanks for the video.

Do you know of any way we can have confirmation on whether it is normal for it to auto limit RX6600 to x4 lanes being in PCIe 3.0?

May be someone having similar hardware can confirm that. I've seen some GPUz screenshots but I think I saw them at x8 even though at 3.0. Not sure though

 

[MK_DEATHANGEL]

I just checked mine, yep I think so. My RX 6950 XT is running in PCIe 3.0 x8 on my X470 motherboard. Seems like I remember coming across that and comparing the performance difference and deciding to go ahead anyway. Not worth it to upgrade from PCIe 3.0 on the sole basis of gaining PCIe 4.0 or 5.0

In comparison, there's not much difference in performance.

Perfect! Thanks. So it does seem to auto reduce it to half bandwidth at 3.0.

 

[MK_DEATHANGEL]

Also, one more thing.
I was using this GPU in my second X16 slot a day before because I needed to Add my sound card into the x1 slot just 2 spaces below my GPU (apparently the space was not good enough to fit both of them) so I placed the sound card in x1 and GPU in the second slot of X16.

I saw same result in GPUz and yesterday after changing the GPU slot to the primary x16 one I still see the same result on GPUz i.e. x4 3.0.

Does this mean that I can run this GPU at any slot regardless without performance changes? And does this mean that I can install my sound card in the second X16 slot without compromising bandwidth on the 1st GPU slot (which stays the same btw x4 3.0) that I've checked as well?

 

[volkgren]

If it's running at x4 in either slot, then yes it wouldn't matter which slot you used.

We may be wrong on the PCIe 3.0 half-speed.

Here is an article from TechPowerUP showing the 6600 XT running in PCIe 3.0 x8.
https://www.techpowerup.com/review/amd-radeon-rx-6600-xt-pci-express-scaling/

 

[MK_DEATHANGEL]

If it's running at x4 in either slot, then yes it wouldn't matter which slot you used.

We may be wrong on the PCIe 3.0 half-speed.

Here is an article from TechPowerUP showing the 6600 XT running in PCIe 3.0 x8.
https://www.techpowerup.com/review/amd-radeon-rx-6600-xt-pci-express-scaling/

Exactly!
So this means that my card is running at 3.0 x4 which is not intended right?
What to do?

 

[volkgren]

Exactly!
So this means that my card is running at 3.0 x4 which is not intended right?
What to do?

That's a good question. Keep in mind it is theoretical speed indicated by maximum bandwidth, which means that the GPU you are using cannot fully saturate that bandwidth, which is why we do not much if any at all performance difference between the different PCIe versions. However, I can understand you wanting the maximum bandwidth possible for your hardware.

 

[MK_DEATHANGEL]

Hello! This might be off-topic but I just switched my GPU to Manli RTX3060Ti and it's showing me 3.0 @X16 now. Strange but the bandwidth is finally here.

 

[MK_DEATHANGEL]

And by the way. I have installed a XIFI Titanium sound card on the other PCI-Express slot and yet the bandwidth is X16!

 

[MK_DEATHANGEL]

I am not closing the thread until we solve this mystery for the sake of knowledge and for anyone who might also be stuck in the confusion I was before.

 

[CountMike]

I am not closing the thread until we solve this mystery for the sake of knowledge and for anyone who might also be stuck in the confusion I was before.

In GPU_Z, click on ? and see what it shows while test is running, With my old Rx 570 it would switch from x16 to x8 when idle.
PS. My present Gigabyte Rx 6600 shows and runs as PCIe x8 gen3 all the time.

 

[MK_DEATHANGEL]

In GPU_Z, click on ? and see what it shows while test is running, With my old Rx 570 it would switch from x16 to x8 when idle.
PS. My present Gigabyte Rx 6600 shows and runs as PCIe x8 gen3 all the time.

Unfortunately, I just sold off my RX6600 but I can confirm that even on stress it never changed from x4 to x8 even

 

[Avro Arrow]

I just checked mine, yep I think so. My RX 6950 XT is running in PCIe 3.0 x8 on my X470 motherboard.

That's weird. Why would it cut its bandwidth in half again just because of that? I would have to go back to my old X370 board to try that with my RX 6800 XT. I've never seen a card do that before.

Seems like I remember coming across that and comparing the performance difference and deciding to go ahead anyway. Not worth it to upgrade from PCIe 3.0 on the sole basis of gaining PCIe 4.0 or 5.0

In comparison, there's not much difference in performance.

Well, yeah, because theoretically, you should still be running at PCI-Express 3.0 x16, not x8. That essentially cuts your bandwidth by 75%.

First it's cut in half because it's PCI-Express 3.0 instead of 4.0 (50% reduction) and then it's cut in half again from x16 to x8 (½ again). There has to be something wrong happening there.

 

[Avro Arrow]

There has to be something wrong there because MSi specifies your board as having two PCI-Express x16 slots. Now, the RX 6600 is physically limited to x8 but that's all it's limited to. It should be using 8 PCI-Express 3.0 lanes, not only 4. PCIeX4 is the problem that exists with the RX 6500 XT (I still don't know why that card has the "XT" suffix).

 

[Avro Arrow]

I just checked mine, yep I think so. My RX 6950 XT is running in PCIe 3.0 x8 on my X470 motherboard.

That's kinda... shocking. Why would it cut its bandwidth in half again just because of that? I'd like to try that but I'd have to go back to my X370 motherboard with my RX 6800 XT. In all my decades of PC gaming, I swear that I've never seen a card do that before.

Seems like I remember coming across that and comparing the performance difference and deciding to go ahead anyway. Not worth it to upgrade from PCIe 3.0 on the sole basis of gaining PCIe 4.0 or 5.0

In comparison, there's not much difference in performance.

Well, yeah, because theoretically, you should still be running at PCI-Express 3.0 x16, not x8. That essentially cuts your bandwidth by 75%. The only way that you

First it's cut in half because it's PCI-Express 3.0 instead of 4.0 (50% reduction) and then it's cut in half again from x16 to x8 (½ again). There has to be something wrong happening there.

 

[majmat]

I've got a RX 6600 and an MSI B450 gaming plus max which has PCIe 3.0, 32GB 3600 and a R5 3600, and it is running in PCIe 3.0 x8 in GPU-Z. I've looked into it, and it runs at that speed, but the card is PCIe 4.0 ,so everyone who's only getting x4 there is something wrong with your set-up, or it's dropping to x4 when idle. Make sure you've got it plugged into the top PCIe slot. Also run GPU-Z's render It's the blue ?

 

[DominoJJ]

I had the same problem with a Sapphire RX6600 on a Gigabyte B450 DS3H board. RX worked as PCIE 3.0 4x and sometimes after bios reset in PCIE 1.1 8x mode. Clearing the PCIE slot with IPA helped.