Gaussian 98 A7 Processor Comparissons (1 CPU & 2 CPU)

Job = LADH Dimer (76723 Atoms) QMMM CIS/3-21G* QM on NADH residue

Gaussian Input file is here.

Route = #p CIS=(Direct, Nstates=4,conver=3)/3-21G* Charge Nosymm

%Mem = 256MB

Compiler options used:

SSE ON = PIII & AMD Athlon XP = PGF77 (3.2-4a) Portland Blas Library -Mvect=sse -r8 (-tp p6) 256 KB Cache
PIII & AMD Athlon XP = PGF77 (3.2-4a) Portland Blas Library -Mvect=256 KB Cache (-tp p6)
AMD Athlon = PGF77 (3.2-4a) Portland Blas Library -Mvect=prefetch (-tp athlon) 256KB Cache

System Specs

Dual Intel PIII 800EB
512MB PC133 Cas3 Ram
IBM 7200RPM Deskstar 46GB HD
MSI Dual PIII Motherboard 694D Via Chipset
GeForce2 GTS 32MB Graphics Card
Redhat 7.1 (Kernel 2.4.1)

Dual AMD Athlon 1.2GHz MP
1GB PC2100 DDR Ram
10,000RPM LVD160 SCSI Drive 36GB
Tyan Thunder K7 Board
or Alternative AMD Board
Redhat Linux 7.1 (Kernel 2.4.7)

AMD Athlon 1.4GHz
256MB PC2100 DDR Ram
Redhat Linux 7.1 (Kernel 2.4.7)

AMD Athlon 1800XP 1.53GHz
1GB PC2100 DDR Ram
Redhat Linux 7.1 (Kernel 2.4.7)



Processors Time for Optimisation (s) Speed as Function of 1xPIII 800 (time for PIII800/time for Proc)
Single Processors    
PIII 800 20955.6 1
AMD 1.2GHz MP 14345.7 1.460758276
AMD 1.4GHz 13469.3 1.555804682
AMD 1800XP 1.53GHz SSE on 13260.7 1.580278567
AMD 1800XP 1.53GHz SSE off 12205.7 1.716869987
Dual Processors    
2 x PIII 800 14916.5 1.40486039
2 x AMD 1.2GHz MP 8421.3 2.488404403


The athlon 1800XP chip is faster than the 1.4GHz Athlon by a factor of 1.103 cf. the ratio of the clock speeds which is 1.093. Thus The new chip design is indeed faster than the old chip design but hardly by the sort of amounts AMD are touting. How they justify the 1800+ tag I don't know. Apparently this is supposed to be a comparison to the standard athlon range and not as is commonly misquoted a comparison to Intel P4's. Thus the PR department would seem to be stretching the truth a bit since a 1.8GHz standard athlon would probably be a lot quicker than the 1800+XP chip.


SSE on the PIII 800 works very well giving a speed up of around 12% for Gaussian.  The Athlon XP now includes SSE extensions but they would appear to be pretty rubbish since turning them on actually slows down Gaussian.