Posted by RBM on December 15, 2009, 8:08 pmPlease Register and login to reply and use other advanced options
Thanks Paul, there is a lot of choice, and as much as I'm more comfortable
with an LGA775, because I've been there before, I'd rather not build
something close to obsolescent. From what you're telling me, it sounds like
the LGA1156 will become the most mainstream Intel socket, so I'll go that
route. I'm looking at an MSI P55-GD80 board and i7-860 cpu as both have
really good reviews. I'll piece the whole system together, then scrutinize
each part until I'm comfortable.
Posted by Paul on December 16, 2009, 5:31 am
Have you looked at the LGA1156 article here ? I see in one
picture of the P55-MD80, it uses a Foxconn LGA1156 socket.
"P55 socket problems"
Wow, the P55-GD80 is $210. Seems to have a pretty generous Vcore.
Lots of phases.
I see it has a six pin "thing" for probing with a multimeter.
A place to stick a multimeter tip, without it sliding off.
I guess that is for measuring voltages other than the ones on
the hardware monitor. I couldn't figure out at first, why there
was some kind of 1x6 over near the main power connector. But that
is what the manual says it is.
It also has a POST display (two digit) for monitoring the POST
sequence of the BIOS. Cheaper than having to install a $25 PCI
POST card when the machine won't start.
Six of the SATA connectors are side mount. One review claims
that is so they don't clash with the video card. Some people
don't like side mount ports.
One reason I downloaded the MSI manual, was to check the PCI Express config.
PCI_E2 ---- x16 x8
PCI_E4 ---- x0 x8
PCI_E5 ---- x4 x4
The implication is, there must be the four chip PCI Express routing
logic on the board somewhere. As I don't think the processor supports
bifurcation on its own. The processor has a x16 interface, that can
be split in two as x8/x8. Now, without external logic, the only wiring
config it would have, is the right-most column. To be able to support
both columns of that table, it would need some chips external to the
PCI Express interface provided by Intel. The P45 chipset motherboards
for LGA775 use the external chip scheme for steering the lanes. The
reason they do this, is so they don't have to put an extra x8 of
lanes on the big chips.
Problem is, I can't identify the steering chips. It is possible they're
using one bigger add-on chip, instead of the four smaller steering chips.
Perhaps the bigger one has an overall lower cost. It could be hiding
under a heatsink.
If you install a single, high power video card in E2, you'll get a x16
at 500MB/sec PCI Express revision 2.0 connection. That is 8GB per second,
and since the PCI Express slot is connected to the processor, which also
has the system memory, the only bottleneck is the speed of the memory
itself. They should have plenty of room for a high bandwidth connection
inside the processor.
If you did use two video cards in E2 and E4, they'd be getting 4GB/sec
The E5 slot (don't know how they're counting these, I'm just going by
the labels in the manual) would be connected to the Southbridge. They
say it is x4 wired, but the bus bandwidth would come through the DMI
connected to the processor. Your SATA drives would share bandwidth with the
E5 slot. Again, not a big deal, but just to show how that one is connected.
And that is why I like Gigabyte user manuals. They have an architecture
diagram, that makes this guessing game easier :-) Gigabyte still chooses
to obfuscate their diagram, but having some diagram to work with, saves
time when checking out the design.
Note that there are two heatsinks on the board, as if the board has
a Northbridge and Southbridge. But there is only one chip in the
chipset. That means the coolers are cooling a Southbridge and ???.
The ??? could be the PCI Express x8 switch logic or something else.
The heatpipe assembly on that board, seems to be fastened with
rivets. If you ever feel the need to remove it, that will be
a significant issue.
This review doesn't go into architecture. And I bet the rivets
prevent reviewers from getting too curious about what is underneath.
The article here, says one of the heatpipe heatsinks doesn't cool a chip.
Somehow, I don't believe that. I think they're hiding stuff under there.
"No floppy disk drive controller is present."
OK, if I look at a picture of the P55 block diagram, it does have
more PCI Express lanes, but you can see that the DMI is a bottleneck
to using all of them flat out at the same time. The x8 worth of
subtending ports are PCIE Revision 2 at 500MB/sec. That is 4GB/sec
max worth of wiring, that can't be supported by 1GB/sec worth of DMI.
The four things connected to x1 ports in my diagram below, would likely
use PCI Express revision 1, so that is 250MB/sec max. A video card
plugged into PCI_E5 could attempt to run at 4x500MB/sec, but be
bottlenecked back to whatever is left of the DMI bandwidth at any
given time. (The PCI Express does transfers when it can, so none of
that actually causes a failure. It just means that there could be
bandwidth peaks, where occasionally the DMI is pretty busy.)
----- x8 PCIE R2.0 ------------- PCI_E2 slot x16 x8
Memory ---- CPU ----- x8 PCIE R2.0 --- switch
| ??? \ x8
| PCI_E4 slot x0 x8
| DMI (1GB/sec up, 1GB/sec down - see Core i5 datasheet)
6*SATA ---- P55 ----- X4 ----- PCI_E5
PCI ---- (SB) ----- X1 ----- VT6315 Firewire
----- X1 ----- JMB363 ------------------------ ESATA
----- X1 ----- RTL8112DL --- Ethernet --- JMB322 ---
----- X1 ----- RTL8112DL --- Ethernet --- IDE
One of the JMB363 SATA ports seems to connect to the JMB322, and the
JMB322 makes two ports out of one port. The JMB322 ports are
likely the vertical ones on the motherboard.
Loads of fun.
Posted by RBM on December 16, 2009, 6:26 pm
I did read the Anandtech article, and was deliberately trying to avoid the
Foxconn socket. In my inexperience, I just assumed I was looking to avoid
any motherboard made by Foxconn. There were a couple of other highly rated
LGA1156 boards at Newegg including an Asus, and a Gigabyte. I'll look into
them as well, and try to find who makes their cpu sockets.
Posted by Paul on December 16, 2009, 8:59 pm
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