i815opt & i815Tweaker 1.0 - BJOne 2001

Be tolerant about this help file, i'm french ;)

USE AT YOUR OWN RISK
BUT YOU MUST KNOW THAT I LOVE WHEN USERS BURN THEIR HARDWARE

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These tools are based on:

INTEL 82815 GMCH DATASHEET (June 2000)
Document Reference Number 290688-001

INTEL 82815EP MCH DATASHEET (November 2000)
Document Reference Number 290693-001

Available at Intel's WebSite (Go to Literature Section).

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These tweakers were designed (formerly for my own usage) to re-enable i815 features
that are disabled by BIOSs when overclocking.

i815opt.exe :     DOS tweaker, to be used from AUTOEXEC.BAT.
i815Tweaker.exe   Windows 9X tweaker, to diagnose & try different settings.

i815 tweakable features:

In both DOS & Windows Tweakers:

AGP 4X Override - Disabled when overclocked
CPU Latency Timer
DRAM Page Closing Policy - Disabled when overclocked
Block New Request Lookahead 
Command per clock - Disabled when overclocked
SM Transmit Stage Bypass - Disabled when overclocked
Host Aperture Cycle Queue Slot  - A i815ep features that seems to be supported by i815e
AGP Sideband Addressing - Should be modified by your video driver
AGP FastWrites - Shouldn't work, maybe for future i815 revisions
Read/Write Power Throttle Control & Throttle Lock - Only tweakable when throttle lock is disabled
CAS / RAS to CAS / RAS / DRAM Cycle Time - SDRAM timings, CAS switching is unstable at this time
SDRAM Refresh Mode
Display of DIMM population

Windows Tweaker add:

AGP Multi-Transaction Timer 
AGP Low Priority Transaction Timer
AGP Data transfer rate - Should be modified by you video driver

So what's up ?

By putting a " C:\UTILS\i815opt.exe -all " in your AUTOEXEC.BAT, i815opt wil enable these features:

- CPU Latency Timer, an option that doesn't seem to be disabled when overclocked.

- Block New Request Lookahead, a mechanism working with the In Order Queue.
   BNR doesn't seem to be disabled when overclocked too.

- Command per cycle, to enable CPC an option called CPC Mask Enable must be disabled.
   CPC has an influence on memory bandwith.
   CPC seems to be DISABLED when overclocked. 

- SM Always Bypass, a memory related option. Will disable a 1 clock latency in i815 memory control,
   but stability may be reduced. SM Always Bypass should disabled (set to normal) when running at 133 Mhz.
   My ASUS BIOS set it when < 140 Mhz, and disables it above this frequency.

- DRAM Page Closing Policy is set to "One Bank".
  "One Bank" should produce better memory bandwith  than "All Banks".
  DPCP seems to be set to "All Bank" when overclocked to gain in stability.

- Host Aperture Cycle Queue Slot (HACQS), an i815ep option that is said (by Intel DataSheet) to be
  RESERVED in i815e (so not supported), but my ASUS CUSL2 bios (not -C, so i815e based) set this bit !

- AGP 4X, by disabling its override. When overclocking, BIOSs disable this AGP 4X.
  But be aware that i815 works only with 1.5V signalling in AGP 4X (2X & 1X work in both 3.3V & 1.5V), 
  so your video card must support 1.5V signalling. 

By using " i815opt -all", you will have a display like this one:

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i815opt v0.99 - BJOne 2001 - Chipset rev 2 - 133 Mhz Operation - AGP mode 1.5V

Current i815 status:
 AGPCTRL: 0x00000081  AGP 4X Override:       Enabled   - (SAFE)   
 MISCC:   0x882a      BNR Lookahead:         Enabled   - (OPTIMAL)
                      CPC Mask Enable:       Enabled   - (SAFE)   
                      SM Always Bypass:      Disabled  - (SAFE)   
 GMCHCFG: 0x4c        CPU Latency Timer:     Enabled   - (OPTIMAL)
                      Memory Arbitration:    Fixed     - (OPTIMAL)
                      Page Closing Policy:   All Banks - (SAFE)
 DRAMT:   0x38        HACQS:                 Enabled   - (OPTIMAL)
                      CAS/RAS2CAS/RAS - DCT:    3/3/3  - 7,9
                      Refresh interval:  100 Mhz/15.6 s 133 Mhz/11.7 s
New i815 status:
 AGPCTRL: 0x00000080  AGP 4X Override:       Disabled  - (OPTIMAL)
 MISCC:   0xa02a      BNR Lookahead:         Enabled   - (OPTIMAL)
                      CPC Mask Enable:       Disabled  - (OPTIMAL)
                      SM Always Bypass:      Enabled   - (OPTIMAL)
 GMCHCFG: 0x44        CPU Latency Timer:     Enabled   - (OPTIMAL)
                      Memory Arbitration:    Fixed     - (OPTIMAL)
                      Page Closing Policy:   One Bank  - (OPTIMAL)
 DRAMT:   0x38        HACQS:                 Enabled   - (OPTIMAL)
                      CAS/RAS2CAS/RAS - DCT:    3/3/3  - 7,9
                      Refresh interval:  100 Mhz/15.6 s 133 Mhz/11.7 s

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When called with no parameters, i815opt displays a more detailled chipset configuration:

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i815opt v0.99 - BJOne 2001 - Chipset rev 2 - 133 Mhz Operation - AGP mode 1.5V

 AGPCTRL: 0x00000081  AGP 4X Override:       Enabled   - (SAFE)   
 AGPCMD:  0x00000102  AGP SBA:               Disabled  - (SAFE)   
                      AGP FastWrites:        Disabled  - (SAFE)   
 MISCC:   0x882a      BNR Lookahead:         Enabled   - (OPTIMAL)
                      CPC Mask Enable:       Enabled   - (SAFE)   
                      SM Always Bypass:      Disabled  - (SAFE)   
 GMCHCFG: 0x4c        CPU Latency Timer:     Enabled   - (OPTIMAL)
                      Memory Arbitration:    Fixed     - (OPTIMAL)
                      Page Closing Policy:   All Banks - (SAFE)
 DRAMT:   0x38        HACQS:                 Enabled   - (OPTIMAL)
                      CAS/RAS2CAS/RAS - DCT:    3/3/3  - 7,9
                      Refresh interval:  100 Mhz/15.6 s 133 Mhz/11.7 s

DIMM 0 Population:
 128 MB, DRAM Tech: 64 Mb
  Front Side: 8 Devices, 8 Mb x 8
  Back Side: 8 Devices, 8 Mb x 8
  Row: 12, Bank: 2 Column: 9
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 128 MB, DRAM Tech: 128 Mb
  Front Side: 4 Devices, 8 Mb x 16
  Back Side: 4 Devices, 8 Mb x 16
  Row: 12, Bank: 2 Column: 9

DIMM 1 Population:
 Empty

DIMM 2 Population:
 Empty

Use i815opt -h for help.


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(In the following paragraph, you are authorized to make a "beep" when a trademark is mentionned).

My personal system is a P3 700e overclocked at 1031 Mhz on an ASUS CUSL2 motherboard,
the FSB and SDRAM are working at 147 Mhz (133:133:33 ratio), SDRAM is working with 222 (CAS/RAStoCAS/RAS) timings & 5,7 Dram Cycle Time (forced).
My video card is a Geforce 1 DDR (Creative Annihilator PRO OEM) modified into a Qudro DDR (overclocked to 158/330 Mhz trough its BIOS), cooled by an ArtiCooler.
I have an SCSI card (Symbios 53C810), a sound card (Vortex2), a network card (3COM 3C905C), 
and an OLITEC 56K/V90 internal modem.

These tweaks works reliably on my system, so i think that many can use the "-all" option.

If you experience some issues, you can try this:
" i815opt -all -!agp " to use every tweaks excepted the AGP 4X one.
" i815opt -all -!hac " to use every tweaks execpted the HACQS (the i815ep feature).

Use " i815opt -h " to have help on other parameters.

I hope that this help maximizing pour system performance. Good luck...

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