Re: K8N-LR PCIe & PCI-X
- From: bman <bjjl@xxxxxxxxxxx>
- Date: Wed, 28 Mar 2007 15:58:46 -0800
Paul wrote:
bman wrote:Thanks for your information and I am thinking of buying the board but I haven't yet. I mainly want the 64bit slot 133mhz for my scsi cards. I did do some more research and I think what the guy was trying to say was that PCIe Express slot only runs at 8x because they split the bandwidth to the Intel's PCI-X bridge. I did download the manual on the board at it says either slot populated will give you 64bit@133mhz but if you use both the slots it will result in 64bit@100mhz. I think I will still buy the board because the PCIe 8x limitation is no big deal. Thanks again.I read on a forum that you are not able to use both PCIe and the PCI-X with an AMD Athlon chip on this K8N-LR. Does the CPU make a difference on how many PCI slots you can use or is it the chip set on the motherboard?
That doesn't make sense to me.
The processor is independent of the subtending busses. In other words, stuff
below the Nvidia 2200 in the picture below, cannot "know" what kind of processor
sits above. If they wanted, Asus could even have used a socket AM2 or a socket F
processor if they wanted. (Asus chose this architecture, as it only requires
one coherent HT bus. Which is why they ended up with the Intel PXH-V, rather
than the more natural fit with an AMD 8131 tunnel.)
While I cannot find a block diagram of your board on some web site,
this is my own guess as to what it looks like. Nvidia 2200 Pro has
20 lanes and 4 links. These would be split x8 for video, x8 for
PXH-V PCI-X bridge, x1 for each of two Ethernet chips, leaving a
couple lanes unused. I don't really know whether they bothered to
connect the Intel PXH-V bridge with x4 or x8 lanes. I think x4 would be
enough to handle 1066MB/sec from a 133MHz PCI-X card transferring 8 bytes
at a time.
S939 <--------> 4 DIMM slots
Processor
|
| 16x16 HT 1000MHz, 4GB/sec up and down
|
Nvidia 2200 Pro
|
+---------+-------+-+-------+------+--------+
| | | | | |
| | x8 | x8 | x1 | x1 | LPC
| | | | | |
PCI32/33 Video PXH-V BCM5721 BCM5721 SuperIO -- Floppy
| | GbE GbE | -- etc...
PCI32/33 PCIX64/133 Flash
| |
ATI_Rage PCIX64/133
XL
|
MiniPCI?
I'm not seeing a reason for this architecture to have any limitations.
The x8 video is 2GB/sec. The PCIX bus at 133MHz is 1GB/sec unidirectional.
Which leaves at least 1GB/sec for the PCI 33MHz bus, hard drives, and
the two GbE Ethernet chips.
Do you have a link to the forum you mention ? I'd like to see what they
think the problem is.
Do you own the board already, or are you thinking of buying it ? In the
Asus forums, there are not many posts, implying very few have been
purchased.
http://vip.asus.com/forum/topic.aspx?board_id=5&model=K8N-LR&SLanguage=en-us
Paul
.
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