PCI-E explanation

[Tsunamijhoe]

Hey guys
I am a bit confused about the specifications of PCI-E x? slots,and was hoping you could help me.

I am looking to exchange my mainboard and need 2 PCI-e 2.0 x8 slots to run my sas controllers on,and was looking at this mainboard ASRock > Z77 Pro4-M

Now,my retailer has this board specified as having:
1 x PCIe 3.0 x16
1 x PCIe 2.0 x16
1 x PCIe 2.0 x16
1 x PCIe 2.0 x1

Which clearly shows it has the 2 slots i need,HOWEVER on Asrock homepage under specifications for the mainboard they have it listed like this:

- 1 x PCI Express 3.0 x16 slot (PCIE1: x16 mode)
- 2 x PCI Express 2.0 x16 slots (PCIE3: x1 mode; PCIE4: x4 mode)
- 1 x PCI Express 2.0 x1 slot

So,what exactly does that mean (PCIE3: x1 mode; PCIE4: x4 mode)???

Can this board use 2 sas pcie x8 cards at the designated speed?

I was looking at this Supermicro | Products | Motherboards | Xeon® Boards | X9SCL-F but it is 3 times as expensive,as i also have to exchange my ram then.

 

[Erick Aguilar]

It would mean that even though they are PCIE X16 physically, two of them are electrically operating in an X4 bandwidth.

As far as I can properly remember, the X16 lane (the one of the op) would be able to run an X8 card. Hell, I've even seen people put in PCIE-1X sound cards in an electrical X16 slot.

Why not purchase two X4 SAS Raid Cards instead of X8?

 

[TheCyberMan]

With that board you have listed only one of your sas controllers will operate at x8 bandwidth if inserted into the x16 slot.

The max bandwidth your second sas controller will operate at is x4 if inserted into the appropriate slot.

So the answer to your question is no i am afraid.

 

[Tsunamijhoe]

With that board you have listed only one of your sas controllers will operate at x8 bandwidth if inserted into the x16 slot.

The max bandwidth your second sas controller will operate at is x4 if inserted into the appropriate slot.

So the answer to your question is no i am afraid.

OK, thank you. However, i have an "old" supermicro saslp-mv8 8port sata controller which i belive is 4x pcie and my new ibm serveraid 1015M is 8x pcie, could i then use both of these,instead of purchasing another ibm card,and have them work at designated speeds?

 

[TheCyberMan]

You can use your current sas controllers just one of them will work at x4 not x8 as long as put in correct slots will probaly affect transfer speeds somewhat but can still be used.

It is always better to use cards that can operate at the same speed unfortunately the PCIe slots on your board do not allow for two cards to operate at x8 speed so you are going to have a speed mismatch.

Using the old card is going to be the same one card running at x8 in x16 slot and then other working at x4 in x4slot.

If you want to run both cards at x8 then a different mobo that has two PCIe x8 slots or x16 slots will be needed.

 

[Tsunamijhoe]

You can use your current sas controllers just one of them will work at x4 not x8 as long as put in correct slots will probaly affect transfer speeds somewhat but can still be used.

It is always better to use cards that can operate at the same speed unfortunately the PCIe slots on your board do not allow for two cards to operate at x8 speed so you are going to have a speed mismatch.

Using the old card is going to be the same one card running at x8 in x16 slot and then other working at x4 in x4slot.

If you want to run both cards at x8 then a different mobo that has two PCIe x8 slots or x16 slots will be needed.

I just had an idea, i have 2 other computers and this mainboard ASUS - Bundkort- ASUS M4A785TD-V EVO is in one of them,now i did a little research,and my Supermicro saslp-MV8 runs at pcie 4x and my IBM serveraid 1015M runs at pcie 8x could i simply exchange my current asrock mainboard for my asus one,as the asus seems to have the slots i can use?

 

[TheCyberMan]

That board supports one PCIe slot running at x16 and one running at x4 so you aren't going to have two slots that can run at x8 speed(bandwidth).

You need a mainboard that has two slots to run at x8 not one slot that runs x16 and the other x4 for them to be both running at same bandwidth.

 

[bobkn]

That board supports one PCIe slot running at x16 and one running at x4 so you aren't going to have two slots that can run at x8 speed(bandwidth).

You need a mainboard that has two slots to run at x8 not one slot that runs x16 and the other x4 for them to be both running at same bandwidth.

And, if you'd ever like to add a PCI-E X16 graphics card, a Z77 based board wouldn't have enough PCI-E lanes to get X16, X8, and X8.

An X79 board would supply enough lanes, but that would require a new CPU (Socket 2011), maybe new RAM (X79 supports quad channel, although it's not required), and the graphics card would be mandatory (no graphics in an LGA 2011 CPU). It'd be expensive, but maybe more apropos two SAS controller cards.

 

[GeneO]

I would look for a motherboard a little more balance in the PCI-E 16 lane slots. Most will do 1 at 16 lanes or 2 at 8 lanes. Are you going to be needing a dedicated graphics card too, or is this a server?

For instance, this board supports 2 PCI-e 16 slots running at 8 lanes each and a third at 4x:

http://www.asus.com/Motherboard/P8Z77V_PRO/

 

[Tsunamijhoe]

That board supports one PCIe slot running at x16 and one running at x4 so you aren't going to have two slots that can run at x8 speed(bandwidth).

You need a mainboard that has two slots to run at x8 not one slot that runs x16 and the other x4 for them to be both running at same bandwidth.

You guys seem to be missing the point..

I have 2 sas controllers 1 Supermicro requires pcie x4 and 1 IBM 1015 requires pcie 8x, this is a server with ONBOARD gfx,so NO GFX Card would EVER be installed,and it is run headless (when it works).

Reason i asked about 2 x8 slots was because i was gonna buy ANOTHER ibm serveraid 1015M, but if i can get it to work using EXISTING hardware,i wounldt need to spend more money on this,i could just exchange mainboards from my server to my other computer.

Why i made this thread was to understand the pcie lane speeds,and if my 2 current controllers could run on any of my current hardware.

And since x8 cards will work in a x16 slot at 8 speed, and the other one is x4 speed,it should work provided my asus board will accept a non-gfx card in the x16 slot (some mainboards require x16 cards in the x16 slot to work)

Am i correct in my asumption? getting these 2 controllers IBM Redbooks | ServeRAID M1015 SAS/SATA Controller for System x and Super Micro Computer, Inc. - Products | Accessories | Add-on Cards | AOC-SASLP-MV8 to work fine on this board? ASUS - Bundkort- ASUS M4A785TD-V EVO

 

[TheCyberMan]

I have already said you can run the two sas controller cards even tho they will run at different speeds if you so wish but there will be a speed diffference or mismatch which may affect and cause a bottleneck between communications between controllers where the faster is always going to be waiting for the slower card may give undesirable affects.

If you so wish to run like that then go ahead and do it the choice is yours at the end of the day and you are happy to do that no problem at all.

You originally said you wanted to x8 slots and the board you listed only had one slot capable of x8 which was a x16slot and a x4 and x1 slot so it did not match your requirement.

Both of those cards will work in the motherboard you orignally posted in your OP but as long as you are aware of the above with regards to communication speed.

 

[Tsunamijhoe]

I have already said you can run the two sas controller cards even tho they will run at different speeds if you so wish but there will be a speed diffference or mismatch which may affect and cause a bottleneck between communications between controllers where the faster is always going to be waiting for the slower card may give undesirable affects.

If you so wish to run like that then go ahead and do it the choice is yours at the end of the day and you are happy to do that no problem at all.

You originally said you wanted to x8 slots and the board you listed only had one slot capable of x8 which was a x16slot and a x4 and x1 slot so it did not match your requirement.

Both of those cards will work in the motherboard you orignally posted in your OP but as long as you are aware of the above with regards to communication speed.

These 2 cards are built like this, nothing i can do about that,and yes i initially asked about 2 x8 slots,because i didnt think i could run my 2 current sas controllers on any of my current hardware at the same time,and thus would have to buy another x8 sas card,but now i dont have to..

The bottleneck wont be the controllers,but the harddrives, as long as the cards get the speed they are designed for,not less everything will be fine..

Like i said,this is a server,so there wont be any copying between the controllers, only added files over gigabit lan, and as long as both controllers can stream a bluray there wont be any problems.

Speed is not an issue, reliability is, i suffer from drive dropouts on my current system,which is why i want to consolidate all compatible hardware into 1 box.

Thank you for your help

 

[GeneO]

No offense, but it was difficult to see what your point was and that is why I asked for more information. You are talking about swapping out an Intel motherboard with an AMD one? I expect you mean CPU and all.

Sure, the Asus motherboard you mentioned said it supports a PCi-e 16 slot @8 and another @4 lanes and the board has an integrated graphics.

 

[TheCyberMan]

No problem if no communication between controllers and agree with above about asus the only thing i would say is to stick to a good brand of mobo like asus or gigabyte as asrock are a budget board and maybe not so reliable as asus or gigabyte and the extra cost of one of those boards i find is worth it.

You are welcome.

 

[Tsunamijhoe]

Hey guys

Well, you know how it is, you have an idea, and then this idea changes . At least we are all on the same page now, and i am sorry for any confusion .

Reason i bought an asrock mb to begin with,was that it had 5 pcix1 slots,which i needed for 5 asrock sata controller cards as i couldnt afford 2 sas controllers at the time, and because i thought it didnt really matter what mb it was as it wouldnt be used for "heavy traffic" use like games or video encoding,but merely as a platform for my popcorn hour to stream movies,also, as a lot of people use old celeron mb for their servers,and they run fine,so why shouldnt a cheap asrock do the same? I at least bought brand new hardware for my server,and even 8GB of ram which is completely overkill.

I do believe however,that the combination of 3 different sata controllers is the cause of my drive dropouts, so before i go and fork out money for a dedicated server mainboard (which i should have to beign with,as it would have saved me money in the long run) i would like to try and see if i can get a stable system using my 2 current server sas controllers,instead of a combination of asrock 2 port sata controllers,and ibm sas controller and mb sata connectors.

So this thread started out one thing,and ended up in a completly different way,sort off

If this works all it has cost me is 2 new SFF-8087 forward breakout cables,instead of 150£ for a server mainboard,which will be last resort.

As for asrock being cheap,well i have used asrock,asus and gigabyte for about 15 years,and i have never had a problem with asrock,not once,in that period i have had 2 asus mainboards fry on me, but this time i think i might simply have overestimated their performance for this type of use, controlling 20+ harddrives.

And yes,i will ofcourse be exchanging complete mb with cpu,coolers and ram between the server and my other pc.. I also have a gigabyte GA-H55-UD3H also with 1 x16 and 1 x4 slot,so if my asus wont accept non-gfx cards in the x16 slot,i can always try that one..

On a plus note, using my asus mb for my server gives the added bonus of it NOT having an UEFI bios,and thus i can flash my ibm serveraid without putting it into a different pc.

Anyways,again thank you so much for your help

 

[TheCyberMan]

No problem i think you are right about the amount of hard drives may have contribute to the frying of the asus boards and yes a server board would be more appropriate running a large number of Hdd's on a controller.

I hope it all turns out good for you you re welcome.