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Modify Windows default IDE latency

Jan 3, 2007
454 (0.11/day)
System Name celer
Processor Pentium 4 650 3.4GHz 2MB L2
Motherboard MSI PM8M3-V
Cooling Thermalright SI-128 SE
Memory 2048MB OCZ 2-3-2-5 2T at 200Mhz
Video Card(s) Sapphire Radeon R9100
Storage 250G Samsung 850 PRO (MZ-7KE256BW) - 1024G WD Black (WD1003FZEX)
Display(s) 19' iiyama ProLite E1980SD 1280x1024 75Hz DVI
Case Eurocase moded
Audio Device(s) onboard
Power Supply Enermax 620W Liberty
Mouse Logitech MX510 red
Keyboard eTech PS/2 keyboard
Software Win XP SP3
Benchmark Scores http://hwbot.org/submission/2455634_
This is a advanced question of how to modify windows to not set the default 128 latency timer for SiS 730 chipset IDE access, but use 144 instead.

Reason - overclocking the chipset (150Mhz) beyond specs (max 133) lower the PCI clock to 30Mhz and it is unable to run stable when on load with latency being only 128. 144 make it rock-stable.

Partial solution - run Latency configurator - LtcyCfg.exe and at startup change the IDE latency to 144. (latency could/should be changed only for multiply of 8, so 128 + 2 x 8 (for safety not only 1 x 8)

Results - machine is stable after the setting.

Problems - booting is still not stable and sometimes just stop, even the machine booted up (with the latency 144 set for IDE) is rock stable.

Bios solution? Not work. There is bios option in the advanced Honey X bios for the PC chips M810L board this thread is all about that set the PCI latency. However having set "PNP OS installed = Yes" you give the OS the power to override the settings at it seems fit - as drivers define?
Setting it to No will insist on the bios settings, but then the machine not boot to windows at all. Futhermore changing the settings does only change the Ethernet latency time, and the Ethernet stuff is pretty happy with good fast latency 32 :) Setting the Ethernet latency to 160 (128 and then 160 are in the settings) did not help anything, of course.

With PCI latency only 128 (hell, that is plenty, but still not enough there...) Prime 95 test always crash at this and always that fast:

That is what the orginal latency settings look:

Setting the IDE interface latency to 144 make the mainboard stable. It is working stable for 24h now :D

So, who can tell me, what and where to change the PCI interface latency in Windows XP SP1.0a I use on this folding machine, so the latency 144 are there since the IDE driver does load?

What informations are need from me to gain?