Motherboard selection dificulties. PCIEx16 and a PCIEx8?

[MaxBurn]

What are the options for a socket 939 CPU with one PCIEx16 slot and one at least PCIEx8 slot? I'm thinking of adding a SCSI card down the line. Would like to get something withing a month or two for my workstation.

Nvidia:
I don't anticipate using SLI but I was considering a SLI motherboard to get that second PCIEx16 slot. I noticed in a couple manuals though that when the motherboard is used for that extra slot as a regular PCIE that it defaults to a PCIEx1 slot instead of the expected x16 slot. Is this true for all motherboards based on the Nvidia SLI chipset?

ULI:
I see that the M1695 either supports two X8 or one X16 PCIE for it's slots and the slower slots are either two PCIEx1 or one PCIEx4. I think a couple variations of this chipset would be best, unfortunately simply not available at the moment. How long of a wait you think? Only thing I see is an Asrock which doesn't suit me.

ATI:
I think I am avoiding them at the moment, will take comments on them though.

 

[Pradeep]

You can switch an SLI board to SLI (giving you two 8x slots), and just use one for video. The other can be used for SCSI etc.

Keep in mind that most PCI-E SCSI cards are RAID controllers, I haven't seen any normal HBA in PCI-E form yet.

 

[sechs]

Yes. In general, "SLI mode" is just a way to redistribute the PCI-Express lanes between the two slots.

Although you're unlikely to notice the difference between a video card at x16 and x8, I was sure that there were some motherboards with enough lanes for two true x16 slots.

 

[MaxBurn]

Yes, I am not sure what difference I would see for video at PCIEx16 and x8, kind of like the difference between AGP4x and AGP8x? ie, not a lot?

As far as the true dual PCIEx16 boards I would sure like to know what does that, I will keep looking.

 

[MaxBurn]

This really blows, you have to dig this out of the users manual most of the time, usually not posted on the product page. Anyway what I have so far for the Nvidia SLI chipset:

Normal mode one PCIEx16 other slot DEAD *OR* two PCIEx8 in SLI mode
-Gigabute GA-K8N Ultra-SLI
-Gigabute GA-K8NXP-SLI
-Tyan Tomcat K8E-SLI (S2866)


Normal mode one PCIEx16 other slot PCIEx1 *OR* two PCIEx8 in SLI mode
-ABIT AN8 SLI series
-Biostar N4SLI-A9

Normal mode one PCIEx16 other slot PCIEx2 *OR* two PCIEx8 in SLI mode
-DFI LANPARTY UT NF4 SLI-DR Expert
-DFI LANPARTY UT nF4 SLI-D
-DFI LANPARTY UT nF4 SLI-DR

NO Normal mode, PCIEx8 in SLI mode only
-DFI NF4 SLI INFINITY

 

[Pradeep]

There will be some chipsets that can do a full 2 * 16x slots, coming out next year. In addition to a couple of x1s and maybe an x4 (I think they have a max of 40 lanes total).

 

[Santilli]

Not a lot of good choices. :x :-?


g

 

[Will Rickards]

I went through the same problem building my system a couple of months ago. I just went for a SLI motherboard and used a PCI scsi card. But I only have one drive on it and at max expect two.

 

[MaxBurn]

Updated list. Please note that many of these boards also have additional PCIEx1 slots not mentioned here.


Normal mode one PCIEx16 other slot DEAD *OR* two PCIEx8 in SLI mode
-Gigabute GA-K8N Ultra-SLI
-Gigabute GA-K8NXP-SLI
-Tyan Tomcat K8E-SLI (S2866)
-Epox EP-9NPA3 SLI manual not posted on USA site, had to go to global site
-Foxconn NF4SK8AA-8KRS


Normal mode one PCIEx16 other slot PCIEx1 *OR* two PCIEx8 in SLI mode
-ABIT AN8 SLI series
-Biostar N4SLI-A9
-Epox 9NPA+SLI manual not posted on USA site, had to go to global site
-MSI K8N Neo4 Platinum/SLI
-MSI K8N Neo4/SLI
-MSI K8N SLI-FI
-MSI K8N SLI-F

Normal mode one PCIEx16 other slot PCIEx2 *OR* two PCIEx8 in SLI mode (these may be a typo in the manual, no other

boards suport the second slot being PCIEx2)
-DFI LANPARTY UT NF4 SLI-DR Expert
-DFI LANPARTY UT nF4 SLI-D
-DFI LANPARTY UT nF4 SLI-DR

NO Normal mode, PCIEx8 in SLI mode only
-DFI NF4 SLI INFINITY

Special Case: two SLI only PCIEx8 *OR* one PCIEx16 (all seperate slots, three slots total)
-eVga 133-K8-NF41-AX - Manual indicates that the three slots are intended for graphics, may work with other cards?

Unable to determine
-ECS ECS KN1 SLI EXTREME - Unclear in manual
-Epox EP-9NPAJ SLi - no manual posted in USA or Global site

 

[MaxBurn]

Here we go, found this:

Asus A8N32-SLI Deluxe (chipset NVIDIA nForce™4 SLI X16)
From the manual:
• In Single Card mode, you may use either the blue or black slot for
PCI Express x16 graphics cards.
• In SLI mode, the PCI Express x16 slots work at the full bandwidth of
PCI Express x16 on each slot for a combined bandwidth of x32.
• Due to NVIDIA nForce4 SLI x16 chipset limitation, if you install a
Dual-GPU graphics card on the blue x16 slot, it runs at x8 speed for
one of the two GPUs.
• Due to NVIDIA nForce4 SLI x16 chipset limitations, this motherboard
does not support two dual-GPU graphics cards (total 4 GPUs)
running in SLI mode.

-Note: says nothing when using one video card and one other card. Hopefully both are PCIEx16? Anyone have any experience with this one?

 

[mubs]

Thanks for all the research, Maxburn. I may need to go down this road myself, so this really helps. Asinine, the way these are designed, no? 2 independent 16x or even 2 independent 8x would have been great.

I have a feeling you won't find what you want any time soon in these "consumer" class boards. On the other hand, workstation boards will probably offer what you want. You may need to go with an Opteron 1xx instead of an A64 in that case.

 

[MaxBurn]

Hopefully we will see regular old SAS/SCSI HBA's in PCIEx4 or less. PCIEx1 is 250MB/s right? That's adequate, but I think they will come out in a PCIEx2 probabbly.

 

[MaxBurn]

Looks like my quest is over:

ASUS A8N-SLI Premium

Manual Page 6-9:

-When in SLI mode Blue slot is PCIEx8 and Black slot is PCIEx8, x4, x2, or x1 for Graphics card (multiple monitor or SLI) RAID or LAN card.

-When in Single video card Blue PCIEX16 is active and Black PCIE is dead.

-This board also has a seperate PCIEx4 and a PCIEx1 slot as well as three PCI. Most flexability I have found yet.

This took what, about all day to find? What a PITA. Major question: is the above functionality a function of the chipset (and all these manufacturers need to fix their documentation) or does the board have to support it (as this one does)?

 

[ddrueding]

Most of the SLI boards I have looked at (actually, all the consumer-level PCI-e boards) have ben limited to 20 channels of PCI-e. Thus the funky behavior and speed divisions amongst the slots. That ASUS A8N32-SLI Deluxe claims that it is using a different chipset. I'd bet that the chipset gives you more channels.

I remember a while back reading about some of Tyan's nVidia PCI-e server level boards haing aditional chips to add PCI-e channels and GbE interfaces, that's where my hunch is coming from.

 

[ddrueding]

Here it is.

Chipset
• AMD-8131™ HyperTransport™ PCI-X Tunnel
• NVIDIA nForce Professional 2200 (CK8-04)
• NVIDIA nForce Professional 2050 (I/O-4)
- Connected to CPU 2
• SMsC Super I/O

Expansion Slots (total of six usable slots)
• Two x16 PCI Express FULL SPEED slots
- Slot1 PCI-E x16 from nForce™ Prof. 2200
- Slot3 PCI-E x16 from nForce™ Prof. 2050
• Two independent 64-bit PCI-X buses
- Slot 4 & 5: PCI-X 100 MHz max. (Bridge B)
- Slot 6: PCI-X 133 MHz max. (Bridge A)
• One 32-bit 33MHz PCI v2.3 (Slot 2)

This board would do it for you

 

[sechs]

On that board, the second chip (with the additional PCI Express lanes) is attached to the second processor. So you'd have to slot two Opterons in there. Not a cheap prospect.

Supermicro is coming out with a similar board.

 

[MaxBurn]

I did run across this for informational purposes:

Feature nForce4SLI X16 nForce4SLI
PCI Express # Lanes/Config AMD: 38 Lanes/Flexible 20 lanes/Flexible

http://www.nvidia.com/page/nforce4_family.html

So I guess theoretically any SLI board you can park any PCIE card in the second slot when in SLI mode and it should work. Looks like all those manufacturers above are totally overlooking this feature and only documenting the ability to put a video card in SLI into that second slot when in SLI mode.

A side note: on the Asus A8N-SLI Premium I noticed this "1 * PCI-E x 1/ 1*PCI-E x 4(x2 mode)" If you add up the PCIE lanes you come up with 21 which is over the chipsets ability so it kicks that PCIEx4 slot down to x2.

Hopefully we will see more of that SLIX16 chipset in the future. ULI is also doing some interesting things with their M1695. Unfortunately both are pretty much unavailable but very close.

 

[Pradeep]

Hey Max, I wouldn't worry about 16x lanes for a simple SCSI card, even the fastest PCI-E RAID controllers max out at 8x, and work happily in a 4x (electrical) slot.

 

[MaxBurn]

Good point Pradeep, Looking cloesly at some pictures I am noticing that some of those PCIEx4 slots have the back end open so you can still put in a wider x8 or x16 card. I am simply hoping that they realize that there isn't a real need for a HBA to be more than say PCIEx2, even a PCIEx1 would be fine. I am obviously making this harder than it should be.


http://sprzet.pclab.pl/zdjecia/artykuly/pila/msi_k8n-neo4/plyta-gora.jpg

http://www.newegg.com/Product/Showi...+939+NVIDIA+nForce4+ATX+AMD+Motherboard+-+OEM

http://www.newegg.com/Product/Showi...+939+NVIDIA+nForce4+ATX+AMD+Motherboard+-+OEM