HOWTO: enable the HLT command on nforce2 chipsets with freeware utils!

graysky · 2004-07-22, 17:41

Forget about using programs like CPUIdle, you can do this yourself with freeware utils. My idle temp lowered from 47C to 41C (chipset temp is 21C) just by using this; there is no negative impact to my GPU either! I should note that this will only lower your idle temp, your full load temp will not change.

Quote:

It activates the C1 (and maybe the C2) function Athlon XP CPU's support. Most mainboard brands have this feature as an option in the bios you can enable and disable. I just found out that EPoX doesn't have that feature. So what you're doing is just using a direct reg tweak to activate it. It's not like you're forcing anything, the Athlon XP chips are made to support this feature so it shouldn't do any damage.
When the CPU is idle the mainboard will send a command to the CPU that will cause a part of the CPU to be deactivated (and therefore not produce any heat). That's why this tweak only works on the idle temp and doesn't change anything on the load temp. Ofcourse as soon as the CPU power is needed the deactivated part will become active again, so it should have any influence on the performance of the CPU.

Remember, this is for nForce 2 chipsets only. I found this by googling, "WPCRSET nforce2" so I suspect that if you google "WPCRSET <your chipset here>" you'll find the correct register to change for your chipset. I know for example that on my old Asus A7M266 board, the values where different.

Please reply to this thread with your results. Maybe some people out there with pCMark2004 or some other synthetic benchmark util can try this and report the results?

Anyway, I found the instructions here.

graysky · 2004-07-22, 18:30

...forgot to add this: if you want to read more of the APCI C1 and C2 modes built into AMD Athlon XP chips, read this document. Chapter 4 talks about the different modes [C1, stop grant, HLT, C2, etc.] which are there from AMD so they're safe to use!

2004-07-31, 04:59

That a lot of work,

Some motherboard already support this. The Abit NF7-S has CPU disconnect function in the newer bios.

Also, if you have SpeedFan, go to Configure-> Advanced. Choose nForce2, there should be ON/OFF option for HALT detect and STOP GRANT disconnect.

graysky · 2004-07-31, 11:17

It's not a lot of work.
My Asus board doesn't have that in the BIOS.
If you're using speedfan, can you do a test? Run the prime95 benchmark without those options enabled, then do it with them enabled and let us know if the results are similar. When I did this experiment with cpuidle, the results with cpuidle enabled were much worse.

graysky · 2004-10-17, 10:23

You guys wanna see some cold temps? Check out this screenshot. It's 34F outside right now and 67F in my office (heater didn't turn on yet). Check out my temps:

http://heaven.earthlights.net/cold.jpg

3200+ no overclock, 1.0 gig crucial ballistix PC3200, using C1 cooling in my original post.

2004-07-22, 18:30	#2
graysky Jul 2004 41 Posts	...forgot to add this: if you want to read more of the APCI C1 and C2 modes built into AMD Athlon XP chips, read this document. Chapter 4 talks about the different modes [C1, stop grant, HLT, C2, etc.] which are there from AMD so they're safe to use! Last fiddled with by graysky on 2004-07-22 at 18:34

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2004-07-31, 04:59	#3
Unregistered 2²·3⁴·19 Posts	That a lot of work, Some motherboard already support this. The Abit NF7-S has CPU disconnect function in the newer bios. Also, if you have SpeedFan, go to Configure-> Advanced. Choose nForce2, there should be ON/OFF option for HALT detect and STOP GRANT disconnect.

2004-07-31, 11:17	#4
graysky Jul 2004 29₁₆ Posts	It's not a lot of work. My Asus board doesn't have that in the BIOS. If you're using speedfan, can you do a test? Run the prime95 benchmark without those options enabled, then do it with them enabled and let us know if the results are similar. When I did this experiment with cpuidle, the results with cpuidle enabled were much worse.

2004-10-17, 10:23	#5
graysky Jul 2004 51₈ Posts	You guys wanna see some cold temps? Check out this screenshot. It's 34F outside right now and 67F in my office (heater didn't turn on yet). Check out my temps: http://heaven.earthlights.net/cold.jpg 3200+ no overclock, 1.0 gig crucial ballistix PC3200, using C1 cooling in my original post.