Athlon XP Oddity

[mwasher]

Yesterday I decided to unlock my new Athlon XP 1900+ AGOGA to see what kind of performance I could get. (In the process of putting the HS/Fan back on my screwdriver slipped, almost cried, but everything came up fine :| ) I then proceeded to benchmark at various FSB/mults to see what would happen. To my (unhappy) surprise a strange trend seemed to appear as I raised the FSB past 150 and lowered the mult below 11.5...

Using 3DMark2001se to benchmark, at 145x11.5 I get around 10,600 3dmarks on my stock GF4. When I turn the clock up to 166x10 I get around *8000* 3dmarks. Almost 2700 LESS! I've tried all sorts of tweaks and whatnot ranging from AGP settings to voltage settings to clock ratios, and nothing seems to explain this strange occurrence. Everywhere I've read has shown a definite increase as FSB increases, why do I have such a dramatic drop?

Update: Yes I've monitored the temps and all is fine. Proc stays below 50C and system stays below 30C.

Athlon XP 1900+ AGOGA
Abit KX7-333R
512MB Corsair XMS PC3200
2x40GB WD Caviar (Raid-0)

Thanks for any help,
Matt

<P ID="edit"><FONT SIZE=-1><EM>Edited by mwasher on 07/12/02 01:56 PM.</EM></FONT></P>

 

[MeTaLrOcKeR]

It might have something to do with the actual clock generator on the MB....at 166 * 10...what does it say your ACTUAL MHz are ?? it SHOULD read 1660MHz......but my guess is that when selected as 166 FSB its actually more like 133.....or mayeb somehwo at 166 all ur PCI devices cant handle the high frequency and same with ur Video card and there crapping out resulting in a lower 3D Mark ?

<A HREF="http://www.anandtech.com/mysystemrig.html?id=13597" target="_new">-MeTaL RoCkEr</A>

 

[mwasher]

It's coming up reading 1660 at 166x10 just as it should. And when I have the FSB at 166 I'm using the 5:2:1 fsb:agpci ratio which puts the agp/pci speeds at 66/33 just as if i was at the default 133mhz fsb... :|

 

[phsstpok]

I'd say that at 150 mhz you're using 4:2:1 ratios. This means FSB is 150mhz but AGP is 75mhz and PCI is 37.5mhz. This is why you are getting better performance. AGP is overclocked.

Edit: You said 145mhz FSB, but you get the idea.

<b>I have so many cookies I now have a FAT problem!</b><P ID="edit"><FONT SIZE=-1><EM>Edited by phsstpok on 07/12/02 02:58 PM.</EM></FONT></P>

 

[lhgpoobaa]

heh
well thats cauz of the kt-333 chipset

at 166 FSB the 1/5 PCI/AGP divider kicks in, lowering the PCI & AGP speeds back to 33 and 66, so you will actually see better performance from a FSB of 165 than 166 cauz of this effect.

of course, running at 166 with your PCI&AGP in spec is better for your components in the longterm... and your system will probably be more stable too.


Proud owner of the <b>Beige Beast</b> :lol: