GPU became pcie x8 after adding m.2 ssd

[37748585862723896]

PC specs

R5 5600

Asus B350F

Rx6800 pulse

M.2 slot x1 , 970evo

Sata x2 , mx500 , seagate buracuda

Wifi card in a x4 slot

 

After adding another 970evo with adaptor, only the 2nd x16 slot runs it in full speed , but then gpu became slower

 

Are there insufficient pcie lanes?

Will remove other hard drive helps?

[Raiyu]

in most manuals its common if you install an m.2 card in a pcie slot the others will become x8

[Raiyu]

5 minutes ago, 37748585862723896 said:

PC specs

R5 5600

Asus B359F

Rx6800 pulse

M.2 slot x1 , 970evo

Sata x2 , mx500 , seagate buracuda

Wifi card in a x4 slot

 

After adding another 970evo with adaptor, only the 2nd x16 slot runs it in full speed , but then gpu became slower

 

Are there insufficient pcie lanes?

Will remove other hard drive helps?

you will need to remove the m.2 card to regain all the lanes for your graphics card

[37748585862723896]

With the m.2 adapter installed on 3rd x16 slot, speed drops from 3500 to 830 MB/s

So the ssd is running at just pcie x1 ?

Or the 3rd slot is only pcie x1?

[Kisai]

25 minutes ago, 37748585862723896 said:

PC specs

R5 5600

Asus B359F

Rx6800 pulse

M.2 slot x1 , 970evo

Sata x2 , mx500 , seagate buracuda

Wifi card in a x4 slot

 

After adding another 970evo with adaptor, only the 2nd x16 slot runs it in full speed , but then gpu became slower

 

Are there insufficient pcie lanes?

Will remove other hard drive helps?

If it became x8, you didn't read the manual for which M.2 slot to use. If you put the M2 into one of the x16 slots, then it would drop it to x8.

 

So just on this basis, you have likely installed your GPU int PCIeX16_3 instead of PCIeX16_1

[37748585862723896]

12 minutes ago, Kisai said:

So just on this basis, you have likely installed your GPU int PCIeX16_3 instead of PCIeX16_

In which order should I put them correctly?

 

1st x16 slot occupied by gpu which covers two slots of pcie x1

So wifi card is on 3rd pciex1

 

Which now leaves m.2 adaptor card

[Jurrunio]

You're not getting full speeds out of both graphics card and M.2 adaptor at the same time. The question is just which one you're willing to sacrifice, the graphics card (use PCIe x16 slot 2) or the M.2 adaptor (PCIe x16 slot 3). The adapter would also block some airflow in slot 2 because it will be quite close to the graphics card

[Alex Atkin UK]

21 minutes ago, 37748585862723896 said:

In which order should I put them correctly?

 

1st x16 slot occupied by gpu which covers two slots of pcie x1

So wifi card is on 3rd pciex1

 

Which now leaves m.2 adaptor card

Its unclear from the manual, it may be you can't use PCIE1_3 and PCIE16_3 at the same time.

This is the main caveat with budget chipsets, they do not allow use of as many slots at the same time as high-end ones.

[Raiyu]

1 hour ago, Alex Atkin UK said:

Its unclear from the manual, it may be you can't use PCIE1_3 and PCIE16_3 at the same time.

This is the main caveat with budget chipsets, they do not allow use of as many slots at the same time as high-end ones.

not just the cheap boards, even the x670e chipset does it, its a thing with asus boards and their m.2 adapters

[Kisai]

1 hour ago, 37748585862723896 said:

In which order should I put them correctly?

 

1st x16 slot occupied by gpu which covers two slots of pcie x1

So wifi card is on 3rd pciex1

 

Which now leaves m.2 adaptor card

PCIEX16_1 is where the GPU should go, always. This is the CPU-connected lanes x16 PCIE 3.0.

 

PCIEX16_2 will drop both 1 and 2 to 8, regardless of what you plug into it, so it's basically useless if you want 16 lanes to the GPU.

 

PCIEX16_3 is chipset and PCIe 2.0, and shares it's 4 PCIe 2.0 lanes with PCIEX1_1 and PCIEX1_3

 

Good gawd I hate this numbering because it makes it difficult to read.

 

Onboard M2 shares bandwidth SATA ports 5 and 6.

 

So you should:

1) Put your GPU in PCIEX16_1

2) Put your main M2 SSD in the onboard M2

3) Not use any additional SSD's. If you want the WiFi you're probably going to have to use the PCIeX1 ports that are available and not X1_1 or X1_3 if you are going to use all the SATA ports, otherwise just avoid SATA 5/6.

 

If you want to use 2 or 3 SSD's, you will want to upgrade the motherboard to one that has the M2's on board and clearly indicates in the manual that it does NOT share the PCIeX16 lanes. For example the B550 Phantom Gaming 4 has 3 M2's of which one of those is an E-Key M2 that a Wifi card can be used in. Or you could buy a premium board that has wifi on it, but generally I feel that these are just bundled "e-key" wifi card implementations.

 

KEEP IN MIND that using all the M2's on most motherboards, including Intel boards, usually means the first SSD is driven by the CPU and the second and third are driven by the chipset, thus their bandwidth is shared regardless. 

 

Generally, and I mean this specifically about AMD platforms, there are "enough lanes" to have two SSD's, the problem is they are not in the right place, and budget chipsets never have the necessary hardware to actually re-assign lanes. Budget chipsets are generally designed for 1GPU/1 SDD systems and generally any other use of the PCIe slots are a compromise. 

 

[37748585862723896]

2 hours ago, Kisai said:

PCIEX16_3 is chipset and PCIe 2.0, and shares it's 4 PCIe 2.0 lanes with PCIEX1_1 and PCIEX1_3

After playing with bios settings, finally managed to run ssd at 2.0x4 , 1800MB/ reads writes but wifi is dead

 

After all, the 3rd slots are only pcie2.0 base speed...

 

[Whatisthis]

Just put it in the second slot and run the gpu on 8 lanes. There is practically no difference in speed, usually within 5%.

 

 

[37748585862723896]

58 minutes ago, Whatisthis said:

There is practically no difference in speed, usually within 5%.

The gpu is already running at pcie3.0 instead of 4.0

and now x16 to x8?

Cant imagine how few % less performance adds up

 

[Whatisthis]

52 minutes ago, 37748585862723896 said:

The gpu is already running at pcie3.0 instead of 4.0

and now x16 to x8?

Cant imagine how few % less performance adds up

 

See the video. That’s on pcie 3 16/8/4 with an Rtx 3070. 
 

There just isn’t that much data going on the pcie bus. 
 

Here is RX 6800 on pcie 3 vs 4. Basically 0 difference. At pcie 3 x8 you will start getting a bit pcie constrained at times but it’s minor.

 

 

[37748585862723896]

9 minutes ago, Whatisthis said:

There just isn’t that much data going on the pcie bus. 
 

However I am seeing many newer gen pcie4.0 x8 low end gpus, 6400 / 7600 , 4060 etc having much worse performance on pcie 3.0 than 4.0 boards,

Which could be exactly my case

[Whatisthis]

2 hours ago, 37748585862723896 said:

However I am seeing many newer gen pcie4.0 x8 low end gpus, 6400 / 7600 , 4060 etc having much worse performance on pcie 3.0 than 4.0 boards,

Which could be exactly my case

The hit is worse the less vram there is on the board and the higher resolution you play at. Your RX6800 has 16gb vram. The hit will be close to zero.

 

here is another article on the 6600 which has half the vram your card has. In most games there is little to no difference.

 

https://www.techpowerup.com/review/amd-radeon-rx-6600-xt-pci-express-scaling/

 

If I was to choose running my drive at half speed or running my gpu in pcie 3 x8, I would choose the gpu every time.

 

I have pointed to evidence multiple times to back that up. If you want to continue to ignore it that’s up to you.

[37748585862723896]

4 minutes ago, Whatisthis said:

The hit is worse the less vram there is on the board and the higher resolution you play at. Your RX6800 has 16gb vram. The hit will be close to zero.

4060 / 3070 /7600 all are 8gb cards

I dont think its ram limited, at least I am gaming on 1080p

 

As this comparison below, some games may have 0 diff, but some may be much slower, and I am more concerned about 1% lows for smoothness

https://youtu.be/0f7NIeNEV78