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M.2 NVMe advice

Level 7
Hi all,

Firstly just want to acknowledge the awesome community in the ROG forums, you guys (and girls) rock!

Long story short, I am using 10th gen CPU in 11th gen Mobo. Hence, the first m.2 slot on the board is not supported.

Luckily however, the Mobo came with a riser card and I have both slots occupied.

Just recently I have noticed red led emitting from the riser card, two lights presumably for two slots in the riser occupied. I have never noticed these lights before and not sure why they are there now. Both drives are working and everything appears normal, except for the fact the ssd is slightly bent in the riser card when installing them.

Does anyone else using the riser card have red led emitting light? Follow up question is, what kind of speed so the dimm.2 slot provide relative to the dedicated m.2 slots?

Secondly, if a single m.2 ssd is installed in the second slot on the Mobo, that shared PCIe gen 3.0 with GPU, resulting in 8x lanes for GPU, what kind of performance loss can be expected?


Level 12
Hi aGovs,
Do you mean a ROG DIMM.2 riser card with ROG MAXIMUS XIII APEX?
May I have the bios version and a video of red led emitting from the riser card?
Have you tried installing other M.2 SSD but red led was still emitting?

For M.2_2 slot (Key M), if you use 10th gen CPU, it supports PCIe 3.0 x4 mode.
For DIMM.2_2 slot (Key M) via ROG DIMM.2, it supports PCIe 3.0 x4 mode.
M.2_2 slot shares bandwidth with PCIEX16_1 and PCIEX16_2. When M.2_2 runs x4 mode, PCIEX16_1 will run x8 mode and PCIEX16_2 will run x4 mode.
For specifications, please refer to our official website and manual.
Thank you.

Hi Starrain thank you for your reply,

Please see image attached of red light being emitted, there are two, as both ports on riser card are occupied.

I don't have any other random ssd to install for troubleshooting. This light has not been noticed before (system running minimum 3 months) and both ssd are seemingly fully operational.

My question for GPU running at PCIe 3.0 8x lanes, the performance aka FPS is widely reported to reduce 1-3%.

My concern is running 10th gen CPU with current gen GPU and want to maximise performance, hence prefer 16x. Or is this a non issue?


Level 12
Hi aGovs,
Thank you for your reply and photo.
I'll consult our tech team more about the red light from ROG DIMM.2 riser card.
The difference of performance between PCIe 3.0 x8 and PCIe 3.0 x16 would depends on games.
It is better to remove SSD in M.2_2 temporarily to experience the difference in gaming by yourself.
Thank you.

Level 12
Hi aGovs,
For the red light from ROG DIMM.2 riser card, is it always on? after power on the pc or boot into windows?
Is it also emitting on bios 1402 with bios all default settings(no OC)?
May I have the following information?
- the serial number of the motherboard via PM
- the brand and the model name of your CPU, RAM, graphics card, SSDs(in each riser cards and M.2 slots) and PSU
(Please check the specific model name of RAM such as G.SKILL F5-6800U4040G16GX2-TZ5S.)
- OS version and OS build
Thank you.

For the red light from ROG DIMM.2 riser card, is it always on? after power on the pc or boot into windows?

Wait, are you implying that the red leds on the DIMM.2 riser card are NOT normal?!

I have an Asus Maximus Extreme Z690 motherboard with a 12900K, and a DIMM.2 riser card with two Gen3 Samsung 970 EVO 2TB NVMe drives inside, both working perfectly.

As far as I know, the red leds on the DIMM.2 have ALWAYS been on (which alarmed me a bit initially since red is normally associated to something not being right, perhaps ASUS should rethink using green leds instead). After reading a bit about it from other users in this very forums I came to the conclusion that this leds are normal and simply mean there are drives attached to the DIMM.2 (e.g.;

Or am I wrong?

Here is a photo I just took of my system. The DIMM.2 red leds are visible at the top of the riser card.


Thanks all for the input,

Yes red light is always on regardless whether PC is booting from sleep mode, hibernation or restart (P30, 40 or AO).

It could be, that I never noticed the red light, therefore assume they are recent, however I did not notice this for many months.

Bios ver.1402

All the information is in the signature

Level 12
Hi aGovs,
Thank you for your information.
I'll forward it to our tech team for further checking.

Thank you Starrain

Look forward to find out what the LEDs are, whether it just shows socket is getting power or a fault with the ssds.

I have performed health check on both using Crystal disk info with all pass