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ASUS Z790 Formula + Crucial T700 SSD = Cannot reach PCIE 5.0 Speeds

dizla
Level 7

As the title suggests, I have recently built a PC with Asus Z790 Formula + i9-14900K + 64GB DDR5 + Crucial T700SSD. I used my current RTX 3080 on this build as I rarely game but mainly do stock and crypto backtesting and needed the extra CPU and RAM power.

I however cannot reach the advertised speeds of the crucial t700 4TB drive. It is supposed to reach seq. read speeds of up to 12500MB/s but my benchmarks never go over 7200MB/s and I am going crazy to diagnose what's wrong. My BIOS and T700 firmwares are up to date. I manually selected Gen5 for the T700 in the bios (which I don't think was necessary but still did) and nothing happened. Crystal Disk Info showing it as operating in PCIE4.0 mode out of PCIE 5.0 available. I am 100% sure that it's sitting on a PCIE5.0 slot (it only has 1 PCIE 5.0 slot for M.2, other 4 slots are PCIE 4.0.

Anyone else with a similar issue?

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1 ACCEPTED SOLUTION

Accepted Solutions

The drive should be automatically detected @ GEN 5.0. There seems to be a few T700 drives experiencing problems, which they've acknowledged. I would contact Crucial and open a support ticket. 

You may want to ensure you haven't accidentally adjusted the Alt PCI Mode switch.

Silent_Scone_0-1707732143517.png

 

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

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8 REPLIES 8

Silent_Scone
Super Moderator

Hi @dizla,

for clarity, can you confirm which m.2 slot you’re using?

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

Cruical T700 - 4TB M.2 drive is mounted on M2_1 (using motheboard's heatsink, mounted under the OLED display), which is the designated PCIE 5.0 M.2 slot.

The drive should be automatically detected @ GEN 5.0. There seems to be a few T700 drives experiencing problems, which they've acknowledged. I would contact Crucial and open a support ticket. 

You may want to ensure you haven't accidentally adjusted the Alt PCI Mode switch.

Silent_Scone_0-1707732143517.png

 

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

The switch was in the 1st step setting. Setting it back to AUTO fixed the issue. I am 10000000% sure that I have not touched it during my installation. Thanks a lot for the heads up.

Thank you for pointing out the PCIe Mode switch, it was the issue on my side on an ROG MAXIMUS Z790 DARK HERO motherboard!

This was set on the middle position, so it used PCIe 4.0, after a shutdown mooving this switch back to the auto mode the crucial T700 was back at Gen5 with the expected writing speeds. I've also forced the PCIE5 mode on the bios instead of the auto mode just to be sure.

I'm curious tho, why even bother to put such a switch on a motherboard if all the PCIe ports are backward compatible anyway?

Thanks for posting the solution. When I first setup my new build using the Asus Dark Hero, I was seeing PCIe 5.0 x4 and getting the advertised speeds. A few weeks later I was having the same issues as everyone else and regardless of my bios settings it was stuck on gen 4. When I saw this post, I checked, and like others the switch was in the middle position. Switched it to auto and I'm back to gen 5. Although between the corsair icue issues I was having with the usb ports, it's likely I accidentally touched the switch without realizing.

i am also having issues with icue, it suddenly disconnects from usb and reconnects and keeps going like that. now it's not working at all. what was your fix for that?

aaaaaaaaaaaaaa4
Level 7

Amazing build! The i9-14900K with 64GB DDR5 memory is a beast for backtesting. While your RTX 3080 is great, have you considered accept bitcoin payments for your future strategies?

Cryptocurrency transactions can be faster and cheaper than traditional methods, especially for international clients. Just a thought! Enjoy your new installation!