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Question NVMe PCI-E Adapter Expansion card?

Fallengod

Diamond Member
Jul 2, 2001
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Just have a question for someone.

I see they make PCI-E Slot Expansion cards to hold NVMe drives. I am just curious as to if there are any drawbacks to using these. IE: Speed/Performance or anything like that.

Any reason to use the slot on the mobo vs one of the pcie adapters? It doesnt hinder using one as a main OS drive does it?

Why you may ask? I just upgraded to a ryzen build. First off, On my new mobo the m.2 slot is literally right above the graphics card(probably not the best design plan), so I was just partly worried about longevity with heat etc since this is data on it.

Second, I know this is new technology but it seems like this design makes it significantly more difficult to remove when you need to. Not that you are swapping out NVMe drives all the time, but I found it pretty annoying versus just unplugging the cables on my sata drives etc. Within the last few weeks I had a few nvme ssds I was benchmarking and I had to remove my graphics card each time to install and remove the damn things. Life would be so much easier with the pcie adapter card I feel like. I would actually prefer if these things sat in drive bays like normal hard drives/sata drives.

The other part of this of course is I am considering having 2 NVMe drives in the system and wondering if that would work as well since the mobo only has ONE m.2 slot.

They only cost like $10-15.
 
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thecoolnessrune

Diamond Member
Jun 8, 2005
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They are functionally the same and comes down to the implementation.

In most cases, at this point, especially on a standard Mobo, the primary M.2 slot on a Mobo should be a PCIe 3.0 4x slot. But this is not always the case. Sometimes the slots are only 2x electrical, and sometimes, especially in the earlier days, they may be PCIe 2.0.

An NVMe expansion card is mostly a passive device with components to fulfill the M.2 electrical and physical requirements, but the signaling it receives is based on the slot you put it in. So your average NVMe M.2 SSD nowadays will want PCIe 3.0 x4 lanes. The bleeding edge obviously has PCIe 4.0 4x lanes.

So look at the specifications of your M.2 slot, then look at the specifications of the slot you want to put the Expansion card in. If they're the same, then you'll see no difference.

To your second point, there is absolutely a 2.5" variant of NVMe drives. These are usually used for enterprise endeavors, as they can take advantage of the extra capacity in a 2.5" enclosure for powerloss protection, larger controllers, larger amounts of NAND, and dissipate higher power consumption. The interface uses the combinations as SAS3, with U.2 connecting to the 2.5" disk, and miniSAS HD, slimline SAS, or Oculink connecting to the motherboard.

There are enclosures available to convert M.2 to a 2.5" U.2 Enclosure: https://www.startech.com/HDD/Adapters/m2-u2-adapter-nvme~U2M2E125
And there are also adapters to convert an M.2 slot or standard PCIe slot to a miniSAS HD Connector: https://www.startech.com/HDD/Adapters/u2-m2-adapter-nvme~M2E4SFF8643 and https://www.startech.com/HDD/Adapters/pcie-nvme-u2-ssd-adapter~PEX4SFF8643

So it can be done, but it of course adds a non-trivial additional cost to a M.2 drive. M.2's primary design facets are around size and cost of implementation. U.2 and similar tech is designed around reliability, durability, and heat dissipation in harsh server environments.Trying to adapt one to the other will reveal the cost differences in those designs.
 
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Fallengod

Diamond Member
Jul 2, 2001
5,773
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Ok. Thanks man. So I just need to check what the speed is of the m.2 slot and compare to whatever the pcie slot would be. My mobo is MSI B450 tomahawk max. Ill have to check it out.

Very cool. I have been out of the computer stuff for a while until, well, I lost my job due to coronavirus, now I have lots of time so I built a new computer with money I dont have. :)

Those U.2 adapter cards are cool and that is what I would be looking for, however I am not paying $40+ for one. :) So ill have to weigh those pros and cons I guess. As I said, this is more of a lazyness thing, versus a real world issue. Most people arnt going to be swapping nvme drives often. I am still a little annoyed the main data OS expensive NVMe drive mounts to above a high temperate high end graphics card...
 
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thecoolnessrune

Diamond Member
Jun 8, 2005
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I tend to agree with you that it's not an ideal space. It's something that's largely determined by available board space and cost of implementation. It's easier from a board routing perspective to put your M.2 slot where there's already a whole board's worth of PCIe signaling already routed.

That all stated, I'll say that under most consumer demands, you should not encounter an issue. Due to heat transference, and airflow, the exhaust air from a GPU is only a fraction of the temperature of the GPU itself. While it is indeed well above ambient, for consumer workloads where your GPU is under heavy use (gaming), your SSD usage should be very low, and therefore temperature rise should not be high. In areas where your SSD is under heavy use (long, sustained file transfers), you're normally not going to be heavily using your GPU.

If you're in a corner case where you're doing long sustained file transfers as well as heavy GPU compute, you're under more of a prosumer or commercial workload, which may behoove you to move the M.2 SSD to a separate expansion card. I personally would not bother moving an M.2 SSD to a U.2 Enclosure, as there's very little to gain (consumer NVMe M.2 SSDs aren't going to support Hotswap), and a lot of cost in doing it.

I'd think for you if you fit in one of those cases, or just want something easier to deal with the disk, you're a great candidate for simply getting an M.2 to PCIe expansion card as you originally asked about. It'll get your M.2 card out from under the GPU, and as long as the slot is tied to the CPU exactly the same as the M.2 slot in question (directly connected to the CPU lanes, not the Chipset lanes, and PCIe 3.0 4x lanes), it will perform identically in the PCIe slot as it would in the M.2 slot. :)
 

Fallengod

Diamond Member
Jul 2, 2001
5,773
10
81
Ok. Thanks man. You have sound logic there. I was just actually thinking to myself before you responded that I probably would never be heavily taxing my GPU at the EXACT same time I am transferring large files around on a nvme ssd. I guess I see the point there. I guess I could look into the heatsink thing for nvme ssds which some others suggested but I am not sure how crucial that would be.

The other part of the reason for my question was, which you probably missed, I am trying to figure out if I can have TWO fast m.2 nvme drives in my computer at the same time as well. This was the other part of my question. I can retire my current 1TB WD Black mechanical HDD and replace with a fast nvme drive allowing for some blistering fast transfer speeds. As well perhaps being more relaible for data storage than a mechanical hdd.

So the expansion pcie m.2 card would possibly be for just adding an additional nvme ssd and keeping the first one in the mobo m.2 slot.
 

thecoolnessrune

Diamond Member
Jun 8, 2005
9,411
355
126
Yeah, the only limits are your slots. As long as you have slots on your mobo, you can toss in as many simple, single disk M.2 to PCIe cards as your system can handle. Things only get fuzzy when you start talking multiple M.2 SSDs in the same PCIe slot (with bifurcation or PCIe switching).
 

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