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Conference giadev::decstation

Title:DECstation PC Conference
Notice:register note 2, see notes 3 & 4
Moderator:TARKIN::LININD
Created:Tue Jan 10 1989
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:7470
Total number of notes:34994

7418.0. "less performance with more memory?" by QCAV02::BHARATI () Fri Apr 18 1997 09:34

    
    We received a complaint from one of our customers who is using autocad
    saying that he is experiencing a degradation in the performance when
    he is upgrading memory from 40MB to 72MB in venturis 5100. 
    We tried winbench97 and wintach here in the lab and we also found
    that the results were better with 40MB than with 72MB.
    Does anyone know the reason for this type of behaviour? or is there
    any tips to get better performance?
    O/S is NT3.51. We have also tried changing the pagefile size
    proportinal to change in memory.
    Also customer says that in compaq and HP machines it does not happen
    so.
    
    Regards,
T.RTitleUserPersonal
Name		DateLines
7418.1Upgrade BIOS.PCBUOA::LIBKINDSam Libkind - PC Support Engineering 276-9465Fri Apr 18 1997 09:542
    Have your customer to upgrade the BIOS to v2.02 from PCBU BBS/WEB site.
    The BIOS name is BG92202A.EXE
7418.2Have you checked out your caching?SNOFS1::RASMUSSENSun Apr 20 1997 22:4312
I am not sure whether this applies to your situation. However, it is not
uncommon for attention to be necessary to the cache subsystem when going beyond
64MB of memory eg. in the TYAN TOMCAT II motherboard I have I need to add a TAG
RAM to allowing caching beyond 64MB. I have also seen (?) the need to add more
cache eg. 128KB to 256KB to ensure caching at high memory levels.

This would explain why system is performing worse ie. you may have some of the
memory effectively running with no cache enabled.

So I suggest you check to see if this may be the case.

Wayne
7418.3QCAV02::BHARATIMon Apr 21 1997 00:353
    
    Thanks, i will check that out.
7418.4QCAV02::BHARATIMon Apr 21 1997 00:395
    
    I knew that the recommended cache size for more than 64MB is 512kb. But
    i can not suggest this to customer because he syas it works as such in
    compaq machines.
7418.5PCBUOA::KRATZTue Apr 22 1997 13:034
    The memory amount vs. performance attributes of the SIS 5511/12/13
    chipset found in the Venturis FX are different than the chipsets
    in the HP and COMPAQ.
    K