[SOLVED] Installing PCI-E 3.0 SSD on MSI H97 Gaming 3 with an adapter

HeartOfAdel

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I have in idea of installing an M.2 NVME on my motherboard through its PCI-E 2.0 x4 slot using an adapter. I'm pretty sure it'll work fine but i don't understand if the speeds of PCI-E 3.0 x16 will drop to x8. I've read the motherboard's manual and there's not a word about the possible speed drop. What do you say?
 
Solution
Your CPU is only connected to the first slot it seems. PCIe 3.0 x16. All the other slots are PCIe 2.0, so they must be coming from the chipset. And the second x16 slot is only wired for 4x.

USAFRet

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I have in idea of installing an M.2 NVME on my motherboard through its PCI-E 2.0 x4 slot using an adapter. I'm pretty sure it'll work fine but i don't understand if the speeds of PCI-E 3.0 x16 will drop to x8. I've read the motherboard's manual and there's not a word about the possible speed drop. What do you say?
  1. If you connect in a PCIe 2.0 slot, thats what it will operate at. No matter what adapter.
  2. If you're planning on using this as the boot drive, unlikely to work.
 
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HeartOfAdel

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  1. If you connect in a PCIe 2.0 slot, thats what it will operate at. No matter what adapter.
  2. If you're planning on using this as the boot drive, unlikely to work.
It will boot 100%. A lot of people have done that, the motherboard supports NVME.
Any SSD with speeds up to 1500-1800 mb will not be bottlenecked by that slot and these speeds are plenty enough for everything.
 

USAFRet

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It will boot 100%. A lot of people have done that, the motherboard supports NVME.
Any SSD with speeds up to 1500-1800 mb will not be bottlenecked by that slot and these speeds are plenty enough for everything.
Really....

Boards of that era, NVMe support is very spotty.
Some boot no problem.
Some, only with the most recent BIOS.
Some, no boot at all.


So, we can contrast your "100%" with all the people and systems for whom it did NOT work.


And regarding the "speed drop".

PCIe 2.0 is ~1/2 a 4.0.
So a drive such as an Intel 660p that would be seen as 1800 (raw sequential) in a PCIe 4.0 slot would be around 900 in a PCIe 2.0 slot.
Barely above SATA III, and totally indistinguishable, performancewise.
 
Dec 17, 2021
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Since you apparently know precisely how everything works, I'm not sure why we're involved at this point.

Huhuhuhu. Incorrect, comrade.

This is why we are involved:

The question you ask is whether pcie 3.0 will be split to x8 / x8 if you use the second slot instead of first.

Depends on mobo but it will have no affect on your graphic card performance. Consider this: a rather intensive graphic card like 1080 ti has a bandwidth of about 1.3 GB/s. A 2x connection of pcie 3.0 will suffice not to bottleneck it (4.0 GB/s). So 8x is still an overkill.

Consider another sitution, which I have experience in: you have a mobo that triggers pcie 3.0 on second slot ONLY if you put your graphics card into the second slot, else is pcie 2.0, and worse, it will only run at 4x speed even if it opens up pcie 3.0. This is still a good slot to work for a power heavy intensive graphic card nevertheless (as of 2021), as the bandwidth overhead of pcie 3.0 4x is 1GB/s x4 = 4 GB/s.

Why would anyone use a second slot instead of a first slot for graphic cards? Sometimes it is broken, or sometimes the slot is just too small because of RAM placement. But nowadays, this is an option if you want to run an NVME at full speed but your second slot only supports pcie 2.0 x4 (like a H97 PRO), this is one way to go about forcing the mobo to provide a pcie 3.0 x4 (or 8x) on the second slot. Flipping the graphic card into the second slot will certainly reduce bandwidth but yet not bottle the graphics card AT ALL. Then you get best of both worlds- a non-bottlenecked nvme blazing at 4GB/s for big file transfers and migrations using NVME, and also a graphic card that still works at pcie 3.0 speed, albeit at 4x (if you mobo is a better one, it would be 8x).

The same strategy will work on mobo with pcie 4.0 only for the first slot but has a pcie 3.0 second slot that can work at 4.0 at specific situations like I mentioned, and you want to run a gen 4 NVME at read/write ~8,000 MB/s.

Never underestimate the intelligence of the hive mind (community).
 
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HeartOfAdel

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Really....

Boards of that era, NVMe support is very spotty.
Some boot no problem.
Some, only with the most recent BIOS.
Some, no boot at all.


So, we can contrast your "100%" with all the people and systems for whom it did NOT work.


And regarding the "speed drop".

PCIe 2.0 is ~1/2 a 4.0.
So a drive such as an Intel 660p that would be seen as 1800 (raw sequential) in a PCIe 4.0 slot would be around 900 in a PCIe 2.0 slot.
Barely above SATA III, and totally indistinguishable, performancewise.
You completely don't understand what you're talking about. Where did you even get that speed on pcie2 x4 would be twice less than 1800mb?

The speed per lane for 2nd gen pcie is twice slower than pcie3, hence its 500mb and 4 lanes are gonna have 2000mb in total, not your anecdotal 900mb. Pcie2 x4 is equal to pcie3 x2.

I thought I'd just ignore your comment but after seeing another response of yours on another thread I just have to say you're a plain misinformer. Stop telling people that the upgrade is useless. This is x3 the speed of sata ssd and a good, meaningful upgrade.
 
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USAFRet

Titan
Moderator
You completely don't understand what you're talking about. Where did you even get that speed on pcie2 x4 would be twice less than 1800mb?

The speed per lane for 2nd gen pcie is twice slower than pcie3, hence its 500mb and 4 lanes are gonna have 2000mb in total, not your anecdotal 900mb. Pcie2 x4 is equal to pcie3 x2.

I thought I'd just ignore your comment but after seeing another response of yours on another thread I just have to say you're a plain misinformer. Stop telling people that the upgrade is useless. This is x3 the speed of sata ssd and a good, meaningful upgrade.
Yes, the benchmark sequential speeds may show that.

The actual user facing difference...you'd be hard pressed to tell the diff in a blind test.