CPUIDLE.FAQ for CpuIdle Win95/98 CpuIdle is Copyright (C) 1997,98 Andreas Goetz. goetz@stud.uni-hannover.de http://www.stud.uni-hannover.de/~goetz FREEWARE Frequently Asked Questions Q: How can I determine if CpuIdle really works on my computer? A: Ahh. That is a little bit difficult as this can't be answered by a software. A thermometer placed on your CPU cooler would do fine. The other way would be to hand-test the temperature of the air flowing from your CPU fan. After running CPUIDLE for some minutes it should be definitely cooler than without CpuIdle running (of course only if you don't put heavy CPU load on your PC during that time). On the other hand it is much simpler to tell if CpuIdle doesn't work. It doesn't if... 1. CpuIdle simply crashes of displays funny error messages. 2. the "About" box shows "disabled" instead of "enabled". 3. you have a Cyrix CPU and the "CPU Info" sheet in the "About" box shows "Suspend on HLT: disabled" Otherwise the chances that it works as promised are quite good, but the ultimate answer can only be given by a thermometer or other temperature- measuring device. If you have a mainboard with the TX chipset and you have an on-board system monitor and temperature sensor chips (LM75/78) you can also use mointoring software like CpuMonitor from http://www.c-lab.de/~chandler/ Q: Ok, I believe that CpuIdle works, but is it safe? A: Well, Win NT does is, Linux does it and OS/2 does it. However a cheap PC with low-quality components could possible be crashed by CpuIdle, as well as by any other application. Q: Does CpuIdle put additional load onto my CPU? A: Read the documentation. No. It just consumes idle time. Measurements with the Winstone benchmark suite have shown that CpuIdle does not decrease the system performance. Q: But my CPU monitor suddenly shows 100% CPU load. How can this be? A: The monitor measures how much idle time he receives and he won't get any since this time is spent in suspend mode. This does not affect normal applications. Q: Will CpuIdle work with Windows98? A: MS should definitely put HLT support into the next version of Windows. But it seems they won't. I don't have access to any Win98 machines and can't test it but I'm told that it works with the beta releases 2 and 3. Q: When I run CpuIdle my computer immediately crashes/ GPF's/ reboots. What's going on? A: I honestly don't have the slightest idea. Sorry. Q: When I run CpuIdle I get random reboots every 10 to 60 minutes. Can you help? A: No, I'm sorry. Very few people have reported this. Most of them use VX chipsets. I don't know if this is an incompatibility. It could also be (with VX chipsets slightly out of fashion) that these computers use power supplies with an out of date design which isn't living up to the mainboard's and CPU's current expectations. Q: When I run CpuIdle my fan turns slower and the voltage on the +5V and +12V lines decreases. Doesn't that mean that the CPU is drawing more power? A: No. Most computer power supplies only compensate higher power demands on the +5V rail, resulting in an increase on the +12V rail when +5V power demand goes up. Koen Gadeyne says in the readme for set6x86: The CPU draws from the +5V rail, but the CPU fan uses +12V, so when the CPU draws more power (due to CPU load), the CPU cooling fan (which is delivered with the CPU by Cyrix) will run a little faster with higher supply voltages, so the significant power drop when the CPU drops into power-suspend mode might cause a noticeable change in the pitch of the buzzing fan sound! It depends on the way the switching power supply is designed. The 12V are generated in the same switching transformer as the 5V, and just the 5V are regulated. This means that the 12V voltage will depend on the current flowing by the transformer primary winding. What happens is that when CpuIdle runs, there is less +5V current so the switching power supply sends less current across the transformer primary and therefore the 12V MUST decrease as the feedback regulation loop exist only in the +5V. That's the reason behind the "fan mystery". Q: When I run CpuIdle I hear terrible static noise or buzzing sound through the speakers attached to my soundcard. What's up? A: This problem can probably be pinned on a poorly designed power supply and/ or soundcard. I can't help you with that, sorry. Q: How can I use the command line switches? A: Make a shortcut to the program, right mouse click on the short cut, go down and click on properties, select the shortcut tab, you can add the switches where it says target. After you have verified that the shortcut works, it is recommended to copy it to your StartUp folder. Q: CpuIdle says "CPUID instruction not available on this machine". What does this mean? A: This means that your CPU either doesn't have the CPUID machine instruction (like 486 CPUs) or that it isn't enabled. On Cyrix CPUs CPUID can be en/disabled. Normally the BIOS should enable CPUID but on some machines it doesn't. If you have a Cyrix CPU and want to enable CPUID you can use tools like set6x86 to do this. Without CPUID CpuIdle will not be able to determine the clock rate of your CPU. However this does NOT influence other CpuIdle functions. Q: When I use DosIdle for DOS sessions, should I need to use CpuIdle when I enter Win95? Will it conflict if I use DosIdle in DOS and CpuIdle in Win95 ? A: CpuIdle is designed to HLT under Win95/98. It works under a Windows DOS Box as well, but is inefficient with ill-behaving DOS programs like Norton Commander (with these programs in a DOS window you can usually feel your other Windows programs run slower). DosIdle should work under older MS-DOS versions (MS-DOS up to 6.2), Windows DOS Box and MS-DOS 7.00 and above (if you restart in MS-DOS mode from Win95/98). To have DosIdle enabled all the time, just install it to your Win95/98 Autoexec.bat AND the DOS 6.22 (or below) Autoexec.bat. This way, DosIdle will take care of anything that's DOS related. And it doesn't conflict with CpuIdle! Q: When I start CpuIdle on my 486 notebook it crashes with a "Fatal Exception 0D in VXD CPUIDLE". What can I do? A: CpuIdle didn't recognize your CPU and tried to use unsupported features. Please start CpuIdle with the -noopt command line switch. Q: Not all CPU features are enabled on my new PII CPU -- what's up? A: I don't have access to a PII machine and couldn't do any testing but it seems as if some PII CPUs don't support all features.