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PCIe3 x4 not working, don't mark solved
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floydstime View Drop Down
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    Posted: 08 Jan 2017 at 9:11am
First off.  The asrock website specifically states that the PCIe Gen 2 x16 lanes are also "PCIe Gen 3 x4" as well.  At one point, my system explorer in BIOS was reading the card as PCIe3 x4, but it was showing 5gbs actual with 10gbs max.  Only after screwing with the BIOS does it state PCIe2 x16 now and it states 4gbs with 8gbs max.  I need help configuring this computer to run PCIe3 x4 on my second PCIe x16 port at 10Gbs pci to pci bridge.  I would appreciate it if you didn't start by telling me that I my board doesn't support it and marking the thread as solved when it is Not solved.  Below is a repost of my first thread.  

So I am having trouble with getting my PCIe 3 x4 to work. There is no option in BIOS, that I have found, to force my second slot to run as PCIe Gen 3. I have a PM961 128 drive, but my read speeds are around 1200 mbs and my write speeds are 800 mbs. It should be twice that. Samsung Magician is showing link speed as 5gbs 10 gbs Max. It should be 10 and 10. Any help would be appreciated... EDIT: I have a 970m Pro3 with FX-6300, AMD HD7970 in second PCIe slot and SYBA M.2 PCIe to PCIe3.0 x4 adapter in my third PCIe slot. The PCIe3 x1 slot is empty. Drive in the Syba is a PM961 128 GB.
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I marked it solved. Plain and simpler it does not support PCIe Gen 3. No AMD board/chipset does except the upcoming Ryzen/AM4 boards. Period.

Put some water on it huh.


From: http://www.asrock.com/mb/AMD/970M%20Pro3/?cat=Specifications:

Expansion / Connectivity

Slots- 2 x PCI Express 2.0 x16 Slots (PCIE2: x16 mode; PCIE3: x4 mode)
- 1 x PCI Express 2.0 x1 Slot
- 1 x PCI Slot
- Supports AMD Quad CrossFireX??and CrossFireX??/td>

Please show me where you see it specifically states it supports PCIe Gen 3 ?



Need more proof?
https://en.wikipedia.org/wiki/AMD_900_chipset_series#AMD_970
Look at that page closer. Even the latest, 990FX, does not support Gen 3.

The ONLY AMD board that does is the ASUS Sabertooth 990FX/Gen3.0 R2.0, and they pull it off with some razzy snazzy engineering and a PLEX chip. Yet even then, it's not a true AMD PCIe Gen 3 solution as the added PLEX chip provides the bandwidth, not anything AMD.
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Originally posted by floydstime floydstime wrote:

First off.  The asrock website specifically states that the PCIe Gen 2 x16 lanes are also "PCIe Gen 3 x4" as well.  At one point, my system explorer in BIOS was reading the card as PCIe3 x4, but it was showing 5gbs actual with 10gbs max.  Only after screwing with the BIOS does it state PCIe2 x16 now and it states 4gbs with 8gbs max.  I need help configuring this computer to run PCIe3 x4 on my second PCIe x16 port at 10Gbs pci to pci bridge.  I would appreciate it if you didn't start by telling me that I my board doesn't support it and marking the thread as solved when it is Not solved.  Below is a repost of my first thread.  

So I am having trouble with getting my PCIe 3 x4 to work. There is no option in BIOS, that I have found, to force my second slot to run as PCIe Gen 3. I have a PM961 128 drive, but my read speeds are around 1200 mbs and my write speeds are 800 mbs. It should be twice that. Samsung Magician is showing link speed as 5gbs 10 gbs Max. It should be 10 and 10. Any help would be appreciated... EDIT: I have a 970m Pro3 with FX-6300, AMD HD7970 in second PCIe slot and SYBA M.2 PCIe to PCIe3.0 x4 adapter in my third PCIe slot. The PCIe3 x1 slot is empty. Drive in the Syba is a PM961 128 GB.


First let's take a look at your board's layout, from the manual:



The PCIe slots are labeled, PCIE1, PCIE2, and PCIE3. Those are simply names to identify the slots. They provide no information about the PCIe revision/speed that the the slot provides, they are just names for the three PCIe slots, 1, 2, and 3.

From your board's specifications:

2 x PCI Express 2.0 x16 Slots (PCIE2: x16 mode; PCIE3: x4 mode)
- 1 x PCI Express 2.0 x1 Slot

Your board has two PCI Express 2.0 (revision/speed) x16 physical slots, numbered 2 and 3.

The PCIE2 slot is x16 electrically (connected to 16 PCIe 2.0 lanes), and the PCIE3 slot is x4 electrically (connected to four PCIe 2.0 lanes.)

Sorry to say, but none of the AMD 900 series chipsets (like your 970) supports the PCIe 3.0 revision. The AMD processors used in these boards do not provide any PCIe lanes to the board, so you only get what is provided by the chipset.

Please see this page for basic specs of the AMD 900 series chipsets:

https://en.wikipedia.org/wiki/AMD_900_chipset_series
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Originally posted by wardog wardog wrote:

I marked it solved. Plain and simpler it does not support PCIe Gen 3. No AMD board/chipset does except the upcoming Ryzen/AM4 boards. Period.

Put some water on it huh.


From: http://www.asrock.com/mb/AMD/970M%20Pro3/?cat=Specifications:

Expansion / Connectivity

Slots- 2 x PCI Express 2.0 x16 Slots (PCIE2: x16 mode; PCIE3: x4 mode)
- 1 x PCI Express 2.0 x1 Slot
- 1 x PCI Slot
- Supports AMD Quad CrossFireX??and CrossFireX??/td>

Please show me where you see it specifically states it supports PCIe Gen 3 ?



Need more proof?
https://en.wikipedia.org/wiki/AMD_900_chipset_series#AMD_970
Look at that page closer. Even the latest, 990FX, does not support Gen 3.

The ONLY AMD board that does is the ASUS Sabertooth 990FX/Gen3.0 R2.0, and they pull it off with some razzy snazzy engineering and a PLEX chip. Yet even then, it's not a true AMD PCIe Gen 3 solution as the added PLEX chip provides the bandwidth, not anything AMD.





No need to get all pissy.  YOU didn't explain it well enough.  However the next post did.  The manual was confusing.  it said PCIe2 x16; PCIe3 x4... WTF am I supposed to think.  So the next post explained it well enough.  PCIe2 is not gen 2 but the second PCIe slot and so is PCIe3.  So either way you are wrong... At least let somebody reply before you close it.  You don't have to be an arrogant jerk on a forum where people are trying to get information or answers.  I was clearly confused, but you being a dick didn't help me with my problem.  I know you think you know everything there is to know about computers, but you don't and neither do I.  Chill out and treat people with some damned respect.  Ouch

Edited by floydstime - 08 Jan 2017 at 2:13pm
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Originally posted by parsec parsec wrote:

Originally posted by floydstime floydstime wrote:

First off.  The asrock website specifically states that the PCIe Gen 2 x16 lanes are also "PCIe Gen 3 x4" as well.  At one point, my system explorer in BIOS was reading the card as PCIe3 x4, but it was showing 5gbs actual with 10gbs max.  Only after screwing with the BIOS does it state PCIe2 x16 now and it states 4gbs with 8gbs max.  I need help configuring this computer to run PCIe3 x4 on my second PCIe x16 port at 10Gbs pci to pci bridge.  I would appreciate it if you didn't start by telling me that I my board doesn't support it and marking the thread as solved when it is Not solved.  Below is a repost of my first thread.  

So I am having trouble with getting my PCIe 3 x4 to work. There is no option in BIOS, that I have found, to force my second slot to run as PCIe Gen 3. I have a PM961 128 drive, but my read speeds are around 1200 mbs and my write speeds are 800 mbs. It should be twice that. Samsung Magician is showing link speed as 5gbs 10 gbs Max. It should be 10 and 10. Any help would be appreciated... EDIT: I have a 970m Pro3 with FX-6300, AMD HD7970 in second PCIe slot and SYBA M.2 PCIe to PCIe3.0 x4 adapter in my third PCIe slot. The PCIe3 x1 slot is empty. Drive in the Syba is a PM961 128 GB.


First let's take a look at your board's layout, from the manual:



The PCIe slots are labeled, PCIE1, PCIE2, and PCIE3. Those are simply names to identify the slots. They provide no information about the PCIe revision/speed that the the slot provides, they are just names for the three PCIe slots, 1, 2, and 3.

From your board's specifications:

2 x PCI Express 2.0 x16 Slots (PCIE2: x16 mode; PCIE3: x4 mode)
- 1 x PCI Express 2.0 x1 Slot

Your board has two PCI Express 2.0 (revision/speed) x16 physical slots, numbered 2 and 3.

The PCIE2 slot is x16 electrically (connected to 16 PCIe 2.0 lanes), and the PCIE3 slot is x4 electrically (connected to four PCIe 2.0 lanes.)

Sorry to say, but none of the AMD 900 series chipsets (like your 970) supports the PCIe 3.0 revision. The AMD processors used in these boards do not provide any PCIe lanes to the board, so you only get what is provided by the chipset.

Please see this page for basic specs of the AMD 900 series chipsets:

https://en.wikipedia.org/wiki/AMD_900_chipset_series



Thank you for your courteous and thorough explanation.  I obviously was confused by the wording.  I was racking my brain for hours trying to figure this one out.  So it turns out my speeds are good with this board.  Do you think it would be wise to pick up an SM951 rather than a PM961 due to my MB limitations of Gen 2?  Since I am only reaching speeds of 1600/800 it seems that an SM951 might be more appropriate for my system.  Or do you think that the speeds would drop in half with that as well.  My son needs an M.2 drive for compiling and complicated stuff like that I don't understand.  Apparently a faster drive will make his life alot easier.  
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Originally posted by floydstime floydstime wrote:


Thank you for your courteous and thorough explanation.  I obviously was confused by the wording.  I was racking my brain for hours trying to figure this one out.  So it turns out my speeds are good with this board.  Do you think it would be wise to pick up an SM951 rather than a PM961 due to my MB limitations of Gen 2?  Since I am only reaching speeds of 1600/800 it seems that an SM951 might be more appropriate for my system.  Or do you think that the speeds would drop in half with that as well.  My son needs an M.2 drive for compiling and complicated stuff like that I don't understand.  Apparently a faster drive will make his life alot easier.  


The SM951 is also a PCIe 3.0 x4 interface PCIe SSD. There are two versions of the SM951, which is confusing, one NVMe, the other "AHCI", simply because it does not used the NVMe protocol.

Unless the difference in price is significant, or you can get a higher capacity drive (500GB instead of 250GB, for example) for a similar price, you might as well keep what you have. If in a few years, you get a new mother board, you move your faster SSD to that board, and no need to buy another.

In real world usage, the difference between 1,000MBs and 3,000MBs is a matter of seconds, unless you are constantly reading and writing 100GB files and folders. Even then, unless a minute makes or breaks you, what's the point? You won't get one half the speed with PCIe 2.0 (5Gbps) instead of PCIe 3.0 (8Gbps) at x4 for each. That's 20Gbps vs 32Gbps. With PCIe 2.0, you will get at least 2/3 of the PCIe 3.0 speed.

We've also found that on the newest Intel systems with PCIe 3.0 x4, with two NVMe SSDs in RAID 0, there is a speed wall at ~3,500MBs, with the newest NVMe SSDs that reach 3,000MBs with one drive.

My point is, you aren't missing a lot of performance with PCIe 2.0 x4. You'll get most if not all of the write speed, with some loss of ultimate read speed. Not worth worrying about, unless you constantly deal with hundreds of gigabytes of data.
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Originally posted by parsec parsec wrote:

Originally posted by floydstime floydstime wrote:


Thank you for your courteous and thorough explanation.  I obviously was confused by the wording.  I was racking my brain for hours trying to figure this one out.  So it turns out my speeds are good with this board.  Do you think it would be wise to pick up an SM951 rather than a PM961 due to my MB limitations of Gen 2?  Since I am only reaching speeds of 1600/800 it seems that an SM951 might be more appropriate for my system.  Or do you think that the speeds would drop in half with that as well.  My son needs an M.2 drive for compiling and complicated stuff like that I don't understand.  Apparently a faster drive will make his life alot easier.  


The SM951 is also a PCIe 3.0 x4 interface PCIe SSD. There are two versions of the SM951, which is confusing, one NVMe, the other "AHCI", simply because it does not used the NVMe protocol.

Unless the difference in price is significant, or you can get a higher capacity drive (500GB instead of 250GB, for example) for a similar price, you might as well keep what you have. If in a few years, you get a new mother board, you move your faster SSD to that board, and no need to buy another.

In real world usage, the difference between 1,000MBs and 3,000MBs is a matter of seconds, unless you are constantly reading and writing 100GB files and folders. Even then, unless a minute makes or breaks you, what's the point? You won't get one half the speed with PCIe 2.0 (5Gbps) instead of PCIe 3.0 (8Gbps) at x4 for each. That's 20Gbps vs 32Gbps. With PCIe 2.0, you will get at least 2/3 of the PCIe 3.0 speed.

We've also found that on the newest Intel systems with PCIe 3.0 x4, with two NVMe SSDs in RAID 0, there is a speed wall at ~3,500MBs, with the newest NVMe SSDs that reach 3,000MBs with one drive.

My point is, you aren't missing a lot of performance with PCIe 2.0 x4. You'll get most if not all of the write speed, with some loss of ultimate read speed. Not worth worrying about, unless you constantly deal with hundreds of gigabytes of data.

Awesome.... you have been super helpful.  This all makes alot of sense.  Thank you!
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Oh, parsec has detailed M.2. You can ignore my post in your other thread.
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Originally posted by floydstime floydstime wrote:


Awesome.... you have been super helpful.  This all makes alot of sense.  Thank you!


Thanks, I appreciate that!

The PCIe revision support level is confused all the time. It can be worse with some Intel systems, where one board (Z77) can use two different processors generations, one that has PCIe 2.0, and the other PCIe 3.0.

The specs say "PCIe 3.0 support", but you must read the fine print where it states that is only true for certain processors.

Even worse IMO is the PCIe x16 slots that are x16 in size physically, but are only connected to x8 or x4 PCIe lanes. Most systems don't provide more than 16 PCIe lanes usable by the PCIe slots. They should be x16 physically to provide mechanical support to a video card, but a board would cost more if all 16 PCIe lanes were connected to every PCIe x16 slot. Some users become very upset when their video cards in SLI or Crossfire are running x8 x8, when they "should" be x16 x16. We all wish that was possible.

Some AMD boards have M.2 slots that are PCIe 2.0 x2, which is really restricting the performance. You've got the best there is for AMD with M.2 slots until Zen systems are available.
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