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Modding The Barton XP To A Barton MP
Dr. Jackie Lee writes "Don't have the budget for an AMD Opteron? There's always a cheaper alternative with AMD's current Barton processors. In this article, we'll show you how to run these new Barton XP processors in SMP mode."
Seriously, though, what gives? Is the only real difference between dual and single processing jumper controlled or is the decision made on the basis of testing - in which case, what might go wrong if you mod these things to run as dual processors?
Even given prevailing levels of cynicism about marketing departments, I would have thought that the potential for chip sales if dual processor boards became more common, would outweigh the loss of margins on the small existing DP business.
Given the main use for multiprocessor boards, I'd be nervous about a mod that might screw data integrity.
Panurge has posted for the last time. Thanks for the positive moderations.
This is NOT a good idea. The MP cores are subject to much more stringent timing variance restrictions. Stick a couple of XP cores in their place, and you'll be getting random RAM errors (actually RAM->CPU bus errors), as well as slowdown due to cache coherency problems.
What We Know Thus Far
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More than a year ago, we reported a hack which you can apply to current Athlon XP processors to enable them to operate as Athlon MP processors. The hack was fairly simple and it involved connecting a certain trace on the Athlon XP processor to allow motherboards to recognize them as an Athlon MP. The trace has been cut in the factory so it's just a matter of connecting them via soldering (if you're brave enough), or just putting conductive paint on them.
The response we received from fellow users were phenomenal and from what we know, many have tried the hack. Although most were successful, some were not that lucky. Here are a few reasons which we can offer at this point in time
# You'll need to ensure both processors are properly modded so that the motherboard can successfully detect and operate the processors in SMP mode. Clean the contacts with acetone or isopropyl alcohol before applying the conductive paint.
# Certain motherboards would only work with the hack since certain users reported that they were unable to get their SMP setup running even though the processors have been properly modded.
# Only certain BIOS versions would allow the board to run in SMP mode. For example, we tested the hack on MSI's K7D Master which had no problems working with BIOS version 1.3 and 1.4B3. Newer BIOS versions somehow did not allow us to run the processors in dual mode even though the processors have already been physically modified.
After our first article, a lot of emails came pouring in and most users were asking if the hack could be achieved with a Thoroughbred core since our initial article was based on the Palomino core. Well, of course it would and we'll be showing some results with a dual Thoroughbred-B core in the later pages. What we've done here is taking another step further with the Barton core. What's interesting with the Barton is that it's now featuring a huge 512KB L2 cache running at full speed. Get a pair of that running in SMP mode, and you'll get a pretty decent workstation-class system going at a really affordable price.
Now, I'm sure most of you are interested to get your hands on a dual processor system based on two Athlon XP 2800+ (Barton). Find out how you can do that in the next few pages.
Modding the Barton Core
The process in modding the Barton core is just about the same as what we've done with the Palomino in previous articles. All you need to do is just to connect the rightmost bridge in the L5 row. That should probably get the processor detected and running in dual mode. However, that's not the end of the story yet as you'll still need to modify a couple of things on the processor to get it running up to speed.
We know that all the Barton cores are made for 333MHz FSB systems and their multipliers were set to run at its predefined frequency. If you put a Barton processor in older motherboards supporting up to 266MHz FSB, you'll probably get a severely underclocked processor and that's probably what will happen if you have the Barton XP running in an AMD 760MPX motherboard.
Naturally, the next logical step is to modify the Barton XP's multiplier. Since most server boards based on the AMD 760MPX chipset has no multiplier adjustments for anything more than 12.5x (at least for the MSI K7D Master), we'll have no choice but to hardwire the multipliers ourselves. OK, here are a few rules which we should observe
# The default frequency of the Barton XP 2800+ is only 2.083GHz (12.5 x 166MHz), so we should try to target a multiplier with a lower resulting frequency at 133MHz (266MHz DDR) FSB. It should at least ensure that your processor will boot-up after the modification. Since there aren't any 15.5x multiplier allocated for the Athlon XP/MP core, we have chosen to hardwire the multiplier to 15x on both the chips.
# Since the Barton cores come with more transistors allocated for the larger 512KB L2 cache, we should see an increase in power consum
Karma: Bad. (As in Good?)
An Athlon MP costs about $40 more than the equivilent MP. You can buy an older ( 1.5Ghz, fine for testing) SMP-capable proc for next to nothing. Developers don't want a modded version of the top-of-the-line AMD chip just to test their threading.
It's hard to be religious when certain people are never incinerated by bolts of lightning.
I have *personally* never saw any hard evidence about this. anybody have a link / site / whitepaper / definitive source?
Now, it is possible that if the SMP portion of the chip have a failure (stuck transistor in a non critical portion, say), they can still sell it as a XP chip, but I don't see why it would require different *timing restrictions*. Believe it or not, it's still just moving data to and from the memory, and having a dedicated path to each CPU even makes this easier.
Granted there are memory control issues (locking, for example) involved, but cache coherency is handled (AFAIK - though my CPU architecture knowledge is very rusty) pretty much the same as a cache miss, so no big impact there.
So, I can imagine that changing an XP to an MP can get you bad things happening if you are unlucky enough to get a chip with a bad SMP block, but I don't think they would become as unstable as you are suggesting.
aaaanyway. I might be talking out of my ass, though. correct me if somebody knows the real straightdope.
My life in the land of the rising sun.
Hence, it is almost useless for scientific applications.
However, as the only P4 CPUs with HT enabled are the most expensive grades, nobody is choosing HT based on value. Maybe a year from now it'll be a compelling option, but right now it's really a non-starter.
here are few mirrors:
Mirror1 - its got a popup.
Mirror 2 - Mirror 2
Mirror 3 -Might get slashdotted.
If you're running effectively two processors on one chip, the heat output will increase as well, and you'll really need that tornado to focus all your cooling on one die. I'd rather have multiple CPUs at lower speeds for more efficient and quiet cooling.
Escher was the first MC and Giger invented the HR department.
you do realise that in a single processor system athlon mp will be still be one single processor.
you still need 2 of these chips and the motherboard to go with it.
the point of this mod is that there is NO barton MP's available.
world was created 5 seconds before this post as it is.
Not to take issue with you, but Barton-core MPs should be released next week.
It's in Japanese, but this article has details (and some photos as well).
A good question. After my dual p2-450 HP Kayak died, and I had the need to buy a new system, I eventually bought another Dual CPU box (DIY Socket 604, 2.4 GHz), mostly because I intend to make heavy use of vmware (workstation & gsx-server).
I must say that one reason to go SMP was that I wanted a system with little or none of the "BS"-parts that seem to end up on consumer motherboards (RealTec-NICs, max 1.5 GB RAM, 6 USB-slots, Firewire etc - you name it) - and which I have no real use for but still have to pay.
Instead, I wanted quality.
I must say, that this is probably the last Dual-System on my desktop for the simple reason that they are god-damned noisy !
Even if you buy a quitend case and a PSU with temperature-controlled fan(s) (which I did), it is still too noisy for me (and the Kayak wasn't silent, either).
Before I put the whole box on one sheet of that air-filled foil that they send HDs etc. to you, the 460W PSU made the whole desk vibrate...
So, if you intend to buy a dual-CPU system, make sure your house/apartement has a place where you can put it, close the door and work via XDM etc. on it (perhaps on a VIA MINI-ITX barebone-ish fan-less PC...), because once I move from my room to a larger apartement, that's sure what I'm going to do !
cheers,
Rainer
Windows 2000 - from the guys who brought us edlin
NVidia GeForce and Quadro cards both use the EXACT same chip. They only differ in the PCI ID. Hence the ability of SoftQuadro to do its magic with driver hacks.
ATI does it too (9700 vs 9500), although in this case many 9500s failed testing as 9700s and will fry if the dead pipelines are re-enabled. (In this case, it's both about providing a lower-end part and about salvaging "reject" chips - 9700s with bad pixel pipelines had those pipes disabled and then were marked as 9500s.)
retrorocket.o not found, launch anyway?
Well... the SCHECK pins are documented in the data sheet for the AMD 761 (uniprocessor northbridge) chip, and the data sheet for the older (T-Bird) non-MP Athlons. Seems rather inconsistent...