Tyan Tiger 2460

[Robert G. Brown]

Dear List,

We've had problems (as have others on this list) getting our 2U
rackmount Tyan Tiger 2460 motherboards to boot/install/run reliably and
stably.  Seth (our systems guy) and I worked on a couple of the boxes
today armed with a 32 bit riser, a 64 bit riser, and an ATI rage video
card and a 3c905m NIC.  

We took the PCI cards off of their frames so we could mount them
vertically directly in the slots for testing.  We also dismounted the
risers so we could try them in different slots as well. The following is
a summary of our findings.

  a) Only the video card would work in slot 1.  Period.  If we put the
3c905 in slot one all by itself (using the BIOS console), the system
would behave erratically, actually mistaking the number and speed of
processors during boot and crashing under heavy network loads if and
when it booted.

  b) If slot one had video or was empty, the system would work fine for
all other vertical configurations.  That is, video in 1, net in 6, video
in 2, net in 3 or vice versa, video in 5, NIC in 2, etc.  I don't know
that we tested every combination but we didn't find another that failed
in all our tests.  Slot 1 alone seems to be the ringer.

It is not a 64 vs 32 bit slot question or a power question per se, as
far as we can tell.  Slots 1-4 are all apparently identical 32 bit, five
volt slots, slots 5+ are 32 bit five volt slots, and both the 3c905 and
ATI are slotted for 3.3/32 bit slots with the extra notch near the
back.  There is no reason that we can see for the 3c905 to work in slot
2, 3, 4, 5, 6, 7 but not in slot 1.

This is further verified by the fact that we had a 2566 to play with as
well, which has two 64/66 3.3 volt slots, and the cards worked perfectly
in them in any order.

  c) Our real torment comes from the riser.  Most riser cards are
designed so they HAVE to plug into slot 1 so that their physical
framework can hold the cards sideways in the remaining room over the PCI
bus.  Plugged into slot 2, there isn't generally room to fit a full
height card (or the support frame) into the remaining space to the side.
With the riser in slot 1, no combination of cards in the riser that
included the NIC would work, and even the video alone in the slot that
should have been a "straight through" connection appeared to have
problems, although a system without a NIC is useless to us so the issue
is moot.  Again, the most common symptom was that the system wouldn't
even get the CPU info correct at the bios level before any boot is even
initiated, and if the boot/install succeeded at all the system was
highly unstable under any kind of load.

The problem persisted, identically, when we put the 64 bit riser (which
we were really counting on to fix things) into slot 1 and plugged the
NIC and video into it, in either order.  We had hoped that the problem
was just the 32 bit riser not correctly connecting lines needed for the
power/clock to automatically set to the needs of the card and that the
64 bit card would "fix" this.  As noted above, the problem is all slot
1, though, in any card orientation even without the riser at all.

HOWEVER, being clever little beasties, we put the dismounted (32 bit)
riser in slot 2 with the extra cabled keys in slots 3 and 4, added the
dismounted PCI cards to any slots we felt like and voila!  The system,
she work perfectly.  Right number of CPUs, flawless boot/install, still
running under heavy load for ten hours or so now.

Since the 3c905 is a highly reliable NIC (and the ATI rage is ditto a
reliable video card and for that matter we also saw the problem earlier
with other NICs, e.g. tulipsj) that work perfectly in many, many
systems, one has to be at least tempted to conclude that this is a
reproducible BUG in the 2460 Tiger motherboard, either in the BIOS or
(worse) in the physical wiring of slot 1. We are reporting it to Tyan as
such to see if they are aware of it (couldn't find it on their website
if they are) and if they know of any fix.  In the meantime, we are
testing a workaround consisting of a riser with a flexible ribbon
connecting the primary slot, so that it can be installed offset from
where it is plugged into the PCI bus.  We hypothesize that if we mount
this riser in the framework (so it sits physically above slot 1 and can
take full height cards) but plug it into slots 2-4, it will work fine
and the systems will stabilize.

Of course the RIGHT solution would be to keep our perfectly good cards
and risers and get Tyan to replace the 2460's (if there isn't a bios
upgrade that fixes the ones we have).  Given the frustration and
downtime and lost productivity we have suffered, giving us 2466
replacements seems reasonable to me:-).

Anyway, this explains to at least some extent why such a wide range of
experiences has been reported for these motherboards on the list.
People who rackmounted them probably had problems, although I'm willing
to believe that there are riser cards out there or particular card
combinations that would "fix" the problem, possibly without the owner
ever knowing it existed.  People who tower mounted them probably did not
have problems, especially if they used an AGP video card or put their
video and NIC into the regular 32 bit slots (or in any event
"accidentally" avoided putting something into slot 1 that wouldn't work
there).  The discussion above may help anybody out there who is still
having problems -- rearrange your cards as described above and all
SHOULD be well and/or replace your riser and/or get Tyan to make it
right.

BTW, so far the 2466 runs fine, as noted by many listvolken.

   rgb

-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu