Question Questions on MoBo (tech basics, but not "lazy beginner" ones)

Jan 8, 2021
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Hi guys,

I did quite a serious research on motherboards and principles of their work. However, a few points are either left unclear or I just wanted to double-check them with you.
Will highly appreciate your comments:
  1. Is it right, that PCIe 4.0 is not the same as PCIe x4. So 4.0 means the interface version, while x4 means the number of contacts in the particular slot (which results in its size), correct?
  2. I've heard that PCIe slot (any - x16, x8 or x4) can be a "non full-bandwidth" one, so devices (in particular GPU!) are to be plugged in full-bandwidth slots to work to their full potential. Does "full capacity" mean that # of slot contacts (e.g. x8) is equal to the # of lanes (= 8) the slot has connection with? Is there any good rule of a thumb to make sure the MoBo I'm going to buy will support simultaneous work of all the devices I plan to connect to it (i.e. these devices won't have to share lanes)?
  3. Is a particular device having (or not) enough lanes a permanent or an adaptive thing? I mean shall e.g. SSD plugged in slot #1 always have only X lanes available for its work or the number of available lanes is volatile and they are shared between devices in real-time, so if e.g. GPU is not much "busy" at a given moment, SSD may have maximum # of lanes it can have according to its spec? What happens in real life if the device gets less lanes than the max. # it supports - SSD writes/reads data slower, GPU generates less fps?
  4. Is it correct that the only consumer devices which support USB 3.1 Gen 2 bus speed (10Gb/s) are NVMe SSD drives (so far)?
  5. High-speed Ethernet port (2.5Gb/10Gb) is needed when big volumes of data are moved between home devices, e.g. PC and NAS. Shall the high-speed port be of any benefit if NAS is used mainly as a home media-server and as a backup server for data volumes less than 1Tb?
 
Hi guys,

I did quite a serious research on motherboards and principles of their work. However, a few points are either left unclear or I just wanted to double-check them with you.
Will highly appreciate your comments:
  1. Is it right, that PCIe 4.0 is not the same as PCIe x4. So 4.0 means the interface version, while x4 means the number of contacts in the particular slot (which results in its size), correct?
  2. I've heard that PCIe slot (any - x16, x8 or x4) can be a "non full-bandwidth" one, so devices (in particular GPU!) are to be plugged in full-bandwidth slots to work to their full potential. Does "full capacity" mean that # of slot contacts (e.g. x8) is equal to the # of lanes (= 8) the slot has connection with? Is there any good rule of a thumb to make sure the MoBo I'm going to buy will support simultaneous work of all the devices I plan to connect to it (i.e. these devices won't have to share lanes)?
  3. Is a particular device having (or not) enough lanes a permanent or an adaptive thing? I mean shall e.g. SSD plugged in slot #1 always have only X lanes available for its work or the number of available lanes is volatile and they are shared between devices in real-time, so if e.g. GPU is not much "busy" at a given moment, SSD may have maximum # of lanes it can have according to its spec? What happens in real life if the device gets less lanes than the max. # it supports - SSD writes/reads data slower, GPU generates less fps?
  4. Is it correct that the only consumer devices which support USB 3.1 Gen 2 bus speed (10Gb/s) are NVMe SSD drives (so far)?
  5. High-speed Ethernet port (2.5Gb/10Gb) is needed when big volumes of data are moved between home devices, e.g. PC and NAS. Shall the high-speed port be of any benefit if NAS is used mainly as a home media-server and as a backup server for data volumes less than 1Tb?
  1. Yes but all others like x1,x4 and x8 can work in x16 slots.
  2. Also yes, even if slot is x16 it could be lower number of PCIe lanes, lanes number as those "x" mean number of PCIe lines available to it. In most MBs, top PCIe sloth has 16 lanes controlled by CPU but some times may drop to 8 lanes if second slot is used. That's mostly in case CPU doesn't have enough lanes to share. Similar thing about second and subsequent slots if they are x16. So called gaming MBs with full support for multiple GPUs may have second slot at same speed.
  3. One of M.2 slots are also is also using some (up to 4) PCIe lanes shared by processor and top PCIe x16 at least. NVME SSDs x4.
  4. No connection between those 2 but yes most quality boards may also have high speed USB too.
  5. Yes faster the better but NAS or any ruter or other devices also need to support such speed. In whole chain weakest/slowest link determines overall performance.
 
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USAFRet

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#5. I've not found a need for faster than gigabit speed for my NAS. Yes, faster is 'better'. But how often are you actually moving data that large from PC to NAS?
A movie that exists on the NAS starts playing immediately. You don't need to transfer the whole thing to a PC before starting to play it. Plays from and remains on the NAS box.
But, an 8GB file takes about 1:12 to move from PC to NAS over a standard gigabit LAN.

Backups? After the first full backup of a drive or volume, you should be doing Incremental or Differential. Not the whole thing again and again.
AN Incremental nightly backup from any of my drives and systems takes but a minute or two.
 
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Thank you guys, you were very helpful!

In most MBs, top PCIe sloth has 16 lanes controlled by CPU but some times may drop to 8 lanes if second slot is used. That's mostly in case CPU doesn't have enough lanes to share.
1. Good point regarding CPU! With CPU lanes taken into consideration, shall the rule of a thumb sound like "the sum of lanes needed for all the current and future devices shall not exceed the # of lanes CPU has"? Or shall it rather be "...CPU has and MoBo's chipset supports"?

One of M.2 slots are also is also using some (up to 4) PCIe lanes shared by processor
2. Right. So if I have a x16 GPU and a x4 M.2 SSD I need 20 PCIe lanes for those 2 devices to work at 100% of their capabilities, correct? Was I right assuming that if SSD gets less lanes than the max. # it supports, it writes/reads data slower, and GPU when the lack of lanes generates less fps?

Is it correct that the only consumer devices which support USB 3.1 Gen 2 bus speed (10Gb/s) are NVMe SSD drives (so far)?
No connection between those 2 but yes most quality boards may also have high speed USB too.
3. Well, probably I formulated it a bit clumsy, but the idea was the following: it makes sense to buy MoBo with a USB 3.1 Gen 2 on board only if you will have a NVMe SSD drive. If you won't - makes no sense (and USB 3.1 Gen 1 a.k.a. USB 3.0 = 5Gb/s will be fine), as no other consumer devices nowadays support USB 3.1 Gen 2 speed (10Gb/s). Agree?

After the first full backup of a drive or volume, you should be doing Incremental or Differential. Not the whole thing again and again.
AN Incremental nightly backup from any of my drives and systems takes but a minute or two.
Thank you for the example, I guess I will be fine with the default 1Gb/s then, taken that the data is not updated each time from scratch, as you've rightly mentioned.
 

USAFRet

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Thank you for the example, I guess I will be fine with the default 1Gb/s then, taken that the data is not updated each time from scratch, as you've rightly mentioned.
I use Macrium Reflect for this backup operation.

Each of the 7 physical drives in my system (list below) are backed up individually, to their own subfolder on the NAS.
Backups/<System>/Drive.
An Incremental image, every night. Keep for 14 or 30 days, deleting the eldest as it goes.

Each system and drive on its own schedule, starting at midnight. Each drive gets its own 30 minute time slot. 12:00, 12:30, 01:00, etc.
Looking through last nights time stamps, the longest one took 9 mins. And that was primarily becuase I was doing a lot of video conversion and editing with that particular drive.

Most were 1 or 2 mins, incl the C drive.

Just as importantly, this is all automated, and happens in the background. I don't have to actually do anything, or manage this manually.

 
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Must be a good reading - thank you! I hope @CountMike will later comment on "lanes" too, as this part is a bit tricky for me and I want to avoid mistakes wherever possible. :)
 
On PCIe lanes, even medium CPU like R5 3600x has 24 PCIe lanes so x16 for GPU + x4 for NVBE is not a problem. 5000 series Ryzen same number but v(ersion)4 which is twice the speed of v3.
That's just for top PCIe and M.2 slots. there will be more from chipset for other PCIe devices.
Here's just one example
https://www.guru3d.com/articles-pages/amd-ryzen-9-3950x-review,4.html

The X570 chipset delivers another 16 lanes PCIe 4.0

When we move to the X570 chipset, it offers 16 additional lanes of PCIe Gen 4.0, these can be re-routed and shared. Per motherboard, things are going to be connected differently. PCIe slots, M.2 SSDs, LAN, card readers or WiFi modules are to be connected via the new interface standard. The configuration depends on the respective motherboard.



As for backup. NAS is probably best solution although can be on expensive side at first but indispensable for multiple networked PCs.
I'm down to one main PC that matters most and ample free time so my solution is removable HDD tray in which I can insert any of my backup HDDs and back up what's needed at that time. BIOS is set to fast and live removal/insertion so I don't even have to turn machine off, it's on 24/7 anyway.
Also using MR but only for system disk and another SSD with games installed on it. Backing them up together so if there's a need (happened few times) they don't go out of sync with each other which may happen if they are backed up separately.
Other data that matter most are in so designated folders so I just copy them to backup disk when a change in contents warrants it. An USB connected disk(s) would also do but unless they are connected by USB3 and better can be slower,
In any case a backup solution that can't be disconnected or otherwise isolated from system is not a true backup.
PS.
Before any backup it's wise to check system and files for malware and integrity. If you backup anything compromised. all you will get is compromised system and/or files.
 
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Hey, @CountMike, what a coincidence - I was actually going to discuss X570 later too (either it or a B550 will finally be my choice). :)

That's just for top PCIe and M.2 slots. there will be more from chipset for other PCIe devices.
So based on what you've said (and the article you've shared):
  • CPU lanes and chipset lanes are summarized, however the way they are re-routed depends on MoBo manufacturer. Different MoBos built on the same chipset may differ in the range of ports and their speeds because of exactly lane re-routing.
  • CPU lanes are directly connected with certain MoBo slots.
  1. Looks like this is direct connection with CPU lanes that makes the slot a "full-bandwidth" one (# lanes = # contacts)?
  2. AMD B550 (not X570!) chipset supports PCIe Gen3, but "CPU’s capabilities are independent and unchanged by the chipset outside of BIOS lock-downs", so if CPU supports PCIe Gen4 it will be available for up to 2 devices. Looks like these are the independent PCIe lanes (for 2 devices) you've mentioned. But what does "outside of BIOS lock-downs" mean here? "Lock down" is just "Set password", but I can't imagine how this may be related to PCIe lanes at all.
  3. Can re-routing of the CPU/chipset lanes be done by a MoBo manufacturer only, or can it be a part of BIOS settings (modified by user) too?
I'm sorry for paying much attention to smth. that is possibly pure basics to you, but I need to be sure I understand this point.

As for the backup - my headache is having certain folders synchronized across different devices, rather than just disks. Imagine, I have a "Music" folder on my home PC and this folder is the Primary/Master one (e.g. all modifications [new files, del/rename files, etc.] are done there). And I have same folder on my NAS and on SD card of my Android phone. Those are Secondary/Slave devices. I want NAS to synchronize data with the home PC at idle time and I want Android device be synchronized with home PC when Android device is connected to home WiFi network. Which app(s) may handle this scenario - what are your recommendations?

Thank you!
 
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Number of PCIe lanes are finite depending on CPU and MB, whichever has less.
For secondary PCIe lines it's chipset and MB that limit their number again whichever is less.
In both cases they are shared with anything that's connected to them and no BIOS cant reroute any because they are hardwired into MB. All BIOS can do is ti limit number of lanes to some some PCIe slots , so the other one(s) ca receive whatever is left.
 
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