athlon XP/MP: the skinny

[elvis]

here's the story:
an associate wants to set himself up a rendering workstation, and came back from dell for a quote for $16k for a dual P4 2GHz.

i jumped online and from a local distributor can get 4 dual AMD 1800+ XP bare-bones systems for just under $9k, which he can easily use as a mini render farm with 3dsmax 4 (frame per machine only, but good enough for the work he does).

the board in question is the tyan tiger S2460 (MP chipset), which seems to have been getting a lot of attention in this forum.

the tyan and AMD sites state quite clearly that this chipset requres athlon MP processors, but from what i read people set these up happily with XP chips.

does the XP do dual? is it just a case of "recommended CPU", or is it a must to use MP chips with the MP chipset. and to follow that up, does the MPX support dual XP's aswell? all feedback muchly appreciated.

[hoe4damoney]

I think MPs have undergone a more rigorous testing regime than XPs...

although it doesn't seem to make a difference.

[Draffa]

and I think the MP's have some kind of `cache-snoop' to avoid duplicating stuff in the two caches.

[TheOtherPhil]

Originally posted by Chris Nolan

Actually its an extra buss called the "snoop buss" (what else?); cache lines may be transferred (via the northbridge) between CPUs over this buss, which eliminates the need for flushing the cache line to memory and reading it back again.

This is also present in the XP processors. The XP's have exactly the same core as the MP. All you get extra for you $$ is unlocked L1 bridges and a guarantee that they work as advertised.

I read this time and again that XP's don't run dual, but they do. ALL AMD cpu's run dual as in the AMD SMP implementation, it is the chipset that handles the SMP not the CPU. The specs on the XP even state it is MP compatible:

Multiprocessing support: point-to-point topology, with number of processors in SMP systems determined by chipset implementation.

elvis grab the XP's and save a load of $$ - I am running 3xdual XP1800 systems and they work perfectly. Just remember not to skimp on good RAM - get Registered ECC stuff.

[ocular]

There is a review article in 14th issue of atomic mpc magazine on AMD 760 MPX.

If you believe the mixed messages emerging from AMD, the MPX chipset only supports the Athlon MP processor.

Seeing as the 760 MPX should be powering much cheaper boards, its in AMD's interest to somehow lock support fot multiprocessing in every cpu but the Athlon MP. THis has allegedly been done; but it seems the physical locking of the MP functions will be at the CPU level and not at the chipset level

They went on and then looked at the ASUS A7M266-D and MSI K7D Master-L motherboards.

Each board is capable of running one or two CPUs, which are suppoded to be Athlon MP processors. However, they both ran stable in MP mode with essentially identical (but cheaper ) Athlon XP processors.

This may be the case because the boards are early revisions, or that our Athlon XP processors are early enough to still be MP compatible.

Reports are mixed on getting non-Athlon MP processors to work, but it is definitely a risky proposal getting it working.

\

Maybe future XP CPUs will be locked?

Maybe if you are buying so many boards you could have the setup tested with XP's?

[TheOtherPhil]

Hey ocular....my S2466N has brand new XP1800's in with the newest stepping. They work fine.

[Leopard]

MP=piece of mind
XP=cheap

choose thy weapon!

If he was prepared for $16k, then he should be able to afford the extra moola for MP's.

Most reports are saying that dual XP's work fine...

[ocular]

Hey ocular....my S2466N has brand new XP1800's in with the newest stepping. They work fine.

The point I was trying to make was that future Athlon Xps may not be MP enabled, so that if you were going down the XP track and have just purchased the latest versions of the CPU if possible have the CPU checked out to make sure it will work on a SMP board, it is rumoured that the XPs may not stay MP enabled.

[NeXuS]

I dont think AMD would do that, they would be shooting them selves in the foot (and basically doin an intel)

They DO NOT guarantee any kind of stablilty with XP's, however I have not seen or heard of pplz having stability troubles due to using XP's and not MP's. Mostly its the AGP graphics card issues causeing wonderfull NMI bluescreens to happen

[TheOtherPhil]

Originally posted by ocular


The point I was trying to make was that future Athlon Xps may not be MP enabled, so that if you were going down the XP track and have just purchased the latest versions of the CPU if possible have the CPU checked out to make sure it will work on a SMP board, it is rumoured that the XPs may not stay MP enabled.

OK, to answer I will say that the XP and the MP use the exact same core. Also, the AMD SMP implementation is controlled by the chipset and not the processor. The only way AMD can block the XP from doing SMP is by forcing mobo manufacturers to use a BIOS to block XP's (this can be done by having the BIOS check the CPUID code) Do you think that this is going to happen? How many users are running dual XP's? How much lost revenue are the mobo manufacturers going to lose by blocking potential customers from using XP's?

I personally think that AMD will wait until the next core/chipset release to stop SMP in their desktop CPU's

[almghty]

You are already paying 9k for the setup right?

Why skimp on the last mile?

[proffesso]

16k is a whole lotta workstation, is it purely for rendering? or content creation as well?.

james,