|Extra Performance & Overclocking
By: Steffen Scheibler, September 18, 2002 Print this article
Getting that little bit extra
Some people can never get enough, so I decided to find out if this system would lend itself to overclocking. A lot of SMP systems are significantly more problematic when it comes to attempting to go beyond their specs, as they are already operating much closer to their physical limits than the average single-CPU system. This is one of the reasons I got PC2400 RAM, but not the main reason, as I shall outline below.
I have assembled a few MPX systems, and I realized quite early on that these systems are extremely picky about what RAM you put in there. Specifications are all nice and cute when written down on paper, but the real world is an ugly and horrible place at times. I, for one, do not recommend putting anything less than PC2400 un-buffered RAM in one of these systems. Registered modules should be CL2, not CL2.5.
As to why, the answer is simple -- for some reason I could never get any CL 2.5 modules to be truly stable in this board. CL 2.5 un-buffered DIMM often wouldn’t boot properly, un-buffered CL2 would only really work reliably when set to 2.5 –- and that applied to all MPX boards. I suppose in order to make the two completely independent CPU buses work, the bus and memory timings are extremely aggressive.
The bottom line is that un-buffered CL2 PC2400 will work at CL2 up to around 140MHz or so. I can get 138MHz stable, at 140MHz I recently got a funny crash I couldn’t explain, so I would be lying if I said 140Mhz was stable. I experienced no problems with registered modules at this speed, however.
If you want to modify your XPs to be unlocked or set a new multiplier, then the MSI is a good board. What do I mean with "A good board?". Simply put, some boards react badly to modified CPUs because they are more sensitive to not-quite-perfect modifications. In the days where a pencil was enough to unlock a T-Bird, some boards simply refused to work reliably, whereas others worked just fine.
The problem was that the pencil mark simply didn’t conduct electricity quite enough. The MSI is very generous with modified CPUs and I experienced no problems, even when I modded one CPU in a very slip-shod manner. 12.5x is the highest you can go, however, getting the XP1900+ running at 1666MHz was no problem, so stability after a successful modification is pretty much guaranteed. The fastest, stable, speed I managed was 1800MHz (144MHz x 12.5) using Kingston registered DDR modules (the Infineon modules won’t even go 138MHz). I didn't even have to increase the VCore -- lucky me.
All in all, I would say that this system is only marginally overclockable -- on one side the FSB cannot be raised by more than 5MHz using PC2400 CL2 and 10MHz using registered RAM. Unlocking the CPUs is easy, but only allows a maximum multiplier of 12.5, which means you can only gain 66MHz from doing this. You could probably buy XP1800s, save $20, and unlock them to 12.5x to make it "more worth your while", but I’d rather spend an extra $20 and buy the XP2000s and not have to fuss around with glue, conductive paint and masking tape for an hour or more -- that is if the XP2000 will run in SMP. The best overclock that can realistically be achieved is 1725MHz (138MHz x 12.5), which will be stable pretty much no matter what hardware you have installed, but its going to take some effort.
This board will also work with the latest XPs (XP2400+ and XP2600+), although I only had one CPU and you will probably have to modify these to work in SMP.
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Performance vs Price
Extra Performance & Overclocking