Samsung SSD 980 at half speed

[wkjdfx]

Hi All,

 

My new Samsung SSD 980 1TB is running at half of the advertised speed on both reading and writing. My 970 EVO Plus on the other hand seems to be fine.

My BIOS is up-to-date, and Z490 should support two PCIe M.2 storage. I'm having a hard time understanding why my 980 is capped at half speed.

This NVMe was just released recently so it is very hard for me to find materials about it.

Does anyone here have a Samsung SSD 980 as well?

[Entropy.]

1 minute ago, wkjdfx said:

Hi All,

 

My new Samsung SSD 980 1TB is running at half of the advertised speed on both reading and writing. My 970 EVO Plus on the other hand seems to be fine.

My BIOS is up-to-date, and Z490 should support two PCIe M.2 storage. I'm having a hard time understanding why my 980 is capped at half speed.

This NVMe was just released recently so it is very hard for me to find materials about it.

Does anyone here have a Samsung SSD 980 as well?

What slot are you using on your motherboard? Iirc it could be that. 

[wkjdfx]

1 minute ago, Brok3n But who cares? said:

What slot are you using on your motherboard? Iirc it could be that. 

970 Plus on top-left and 980 on bottom-right.

[Entropy.]

Just now, wkjdfx said:

970 Plus on top-left and 980 on bottom-right.

Yes, that *may* be the problem. Again iirc, the only slot that'll take advantage of the full speed would be the top one, which is connected directly to the cpu, the other is to the chipset. I'm not 100% sure but that could be the problem. 

[Aaron_T]

Seems like too large of performance dip...

 

Try swapping the slots that your SSDs are installed in and re-running the performance tests. May also want to look into newest Samsung NVMe drivers.

[wkjdfx]

31 minutes ago, Brok3n But who cares? said:

Yes, that *may* be the problem. Again iirc, the only slot that'll take advantage of the full speed would be the top one, which is connected directly to the cpu, the other is to the chipset. I'm not 100% sure but that could be the problem. 

Afaik both slot are connected to the chipset. The two slots should be equivalent.

[Chris Pratt]

Z490 doesn't have PCIe 4.0. The 980 Pro is a PCIe 4.0 drive. If you run it at PCIe 3.0, half speed is exactly what you're going to get because the bus only has half the bandwidth it's rated for.

 

Sorry. 980, not 980 Pro. I saw 980 and "half speed" and brain went instantly to PCIe 4.0.

[wkjdfx]

Alright I think I just fixed the problem. The BIOS was automatically using x2 mode for the 980 slot for some reason, even though I am not using any SATA port that is sharing its bandwidth. Manually setting the slot to be x4 mode in the BIOS fixed the problem.

[wkjdfx]

2 minutes ago, Chris Pratt said:

Z490 doesn't have PCIe 4.0. The 980Pro is a PCIe 4.0 drive. If you run it at PCIe 3.0, half speed is exactly what you're going to get because the bus only has half the bandwidth it's rated for.

It's a 980, not 980 PRO. Thanks for the response tho

[Chris Pratt]

Just now, wkjdfx said:

It's a 980, not 980 PRO. Thanks for the response tho

Yeah. I noticed my mistake, but not quick enough, apparently.