contents:
1. Athlon software cooling
2. Older CPUs - K6, K5, Pentium III/II/I and so on
3. Cool'n'Quiet equivalent for Athlon XP
1. K7 Athlon software cooling
Aka "disconnect on HLT", aka "disconnect on STPGNT" aka "S2K bus disconnect"
Here, the CPU goes sleeping after a special command is recieved. It's the only possibility without hardware modding for a K7 Athlon to save power at idle.
This feature is supported since the very first Athlon/Duron CPUs.
More detailed
When there is nothing to to, the operating system has the possibility to send three different signals to the CPU:
no operation, HLT, STPGNT.
Windows 9x versions without ACPI installed use "no operation".
Windows 2000 and XP without ACPI installed use HLT.
All Windows' with ACPI installed use HLT.
Linux without ACPI kernel support use HLT, with ACPI kernel support they use STPGNT.
There is a Linux-Howto available.
Once the chipset recieves a HLT or STPGNT is disconnects the FSB from the CPU. The CPU now uses a divider (8...512) to clock itself down significantly.
There is no power saving difference between the HLT and the STPGNT command.
Enabling this feature doesn't bring any performance hit, as xbitlabs.com showed in this arcticle under "Heat Dissipation".
Chipset support
VIA - Best compatibility. Works flawlessly on my KT133,KT266a,KT333,KT600. Supports disconnect on STPGNT, supports disconnect on HLT since the KT266.
Nvidia - Nforce supports at least disconnect on STPGNT. Nforce2 supports disconnect on HLT. But only some boards are working - the others are getting instable. Search for experiences on your favorite board on google.
SIS - ECS K7S5A does not work. But chipsets generally support it.
Have a look in the Linux-Howto in order to find out wether your board supports the feature. If it says "works without ACPI" it also disconnects on HLT.
How to enable
Athlon XP mainboards supporting software cooling directly through the BIOS
You have to look for "S2k bus disconnect" in you BIOS.
According to xbitlabs.com
ASUS A7V8X v1.04
EPoX EP-8K9A2
Gigabyte GA-7VAXP v1.0
Gigabyte GA-7VAX v1.1 (one SPCR user could not confirm this)
Gigabyte GA-7VA v1.0
(all are KT400) should have implented this.
In the silenthardware.de forum the Abit NF7-S v1.4 was confirmed.
Abit NF7-S v2.0 (nforce2) and
MSI KT3Ultra (KT333) confirmed here at SPCR
MSI KT6 Delta (KT600) confirmed by my myself
Albatron KX18DS Pro Nforce2 Ultra confirmed at 3dcenter.de
Via 3rd Party Software
Now your BIOS does not support the feature. All you have to do now is to find a software which changes some registers in the north- or southbridge of you motherboard and thus enabling the disconnect.
S2kCtl - it's free and has the options to alter the divisors. Still developed, should support many mainboards.
CoolOn - freeware, supports VIA, SIS, nVidia chipsets. Option to alter the divisors.
Vcool - it's free but it's developing very slow. It supports VIA boards until the KT400. There is no option to change the divisor, but options to change some PCI settings which is good for troubleshooting.
CPUIdle If the the freeware does not work, try this shareware. Should support every chipset.
Special case: Windows 9x without ACPI and chipset only supports STPGNT but operating system sends HLT
You need a software which overrules the system idle thread with a new idle thread.
Vcool issues STPGNT signals. With CPUIdle one can select between HLT ("S1 state") and STPGNT ("C2 state"). RMClock issues HLT.
Powerusers: WCPREdit
With this program you can edit the registers of your northbridge interactively. It's good for looking behind the scenes or if you are not satisfied with the other programs. It's good to get a .pcr file for your chipset. George Breese has some for Via chipsets.
But it also works without the pcr files. Just go to the Linux-Howto and have a look at the setpci commands:
Code: Select all
enable: setpci -v -H1 -s 0:0.0 52=$(printf %x $((0x$(setpci -H1 -s 0:0.0 52) | 0x80)))
disable: setpci -v -H1 -s 0:0.0 52=$(printf %x $((0x$(setpci -H1 -s 0:0.0 52) & 0x7f)))
One drawback of WpcrSet: after S3 standby mode, the bit is not set on my MSI KT266 Pro2.
Once you've enabled the disconnect listen to some music from you PC and try to create a large RAR-archive in order to test wether your PC is stable.
Troubleshooting
Ok, now you've enabled your disconnect and you noticed strange sound coming out of the speakers or CRC-Errors while packing with WinRar? Time to turn some knobs a bit.
- try to enable as many PCI options as possible in the BIOS. Vcool or WPCREdit can do this from Windows. For my KT133, "Master Read Caching" is cruical. "CPU-to-PCI Write Buffer" and "Delayed Transactions" are also good tries. Note: Users of the VIA 686B-Southbridge shouldn't enable "Master Read Caching" and "Delayed Transactions".
- S2kCtl and CPUMSR have the option to change the "Bus frequency divisors". The lower they are, the less latencies in the system.
- CPUMSR additionally offers "clock change timing" settings. Here you can select to perform the change from low frequency to high frequency faster
- RMClock has some more advanced timing settings, also autostart
- get the latest BIOS. Your manufacuturer may have changed some other PCI settings
2. Older CPUs - K6, K5, Pentium III/II/I and so on
Those CPUs also support going to sleep while recieving HLT. There is no disconnection necessary. But the operating system has to supply a HLT command. Linux is okay, but Windows may not. You may need a program which replaces the idle thread and issues HLT commands.
- download KCPUCooler or WinCooler
- or search for "Rain" or "Waterfall" on google
3. Cool'n'Quiet equivalent for Athlon XP
Athlon XP CPUs since the Palomino/Morgan can be changed to be a mobile CPU. The main ressource for this mod is CPUHeat.wz.cz.
It enables PowerNow! and works with nearly all chipsets except the nForce 1+2. Now you can adjust the multiplier under Windows. When you had an unlocked CPU before, you where previously not allowed to change the multiplier in Windows. When you had a "superlocked" CPU you are now able to change the multipliers in Windows only.
What are the advantages of this mod for the silent crowd?
Frankly speaking, not as nearly as many as with Cool'n'Quiet. The problem is that you can't change the voltage on the fly. Only nForce 2 boards are supporting this, but they don't support PowerNow! What a pitty, isn't it? You only have additional saving over "Disconnect on HLT/STPGNT" if you lower the voltage. So for now this tweak could be used as a cool geek toy or as a on-demand limiter of the CPU frequency when you want to have a little bit less noisier.
But the change of the frequency can also be done by other software by changing the FSB - even with a locked CPU:
ClockGen: http://www.cpuid.org/clockgen.php
8rdavcore for nForce2 users: http://www.hasw.net/8rdavcore/
CPUFSB: http://www.cpufsb.de
SetFSB
EDITS:
apr/02/05: CoolOn and KCPUCooler and WinCooler added
sept/01/06 RMClock added
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Suggestions very welcome!