I'm messing with various options for keeping my new P4 3.2 CPU cooled, trying to strike a balance between noise and cooling. I am monitoring the CPU temperature with a software utility as I mess with various things.

Two questions:

1. Where on the motherboard is the temperature sampled from? Within the CPU, or somewhere outside of it?

2. What's a good ceiling I should put on sustained CPU temperature? For instance, while playing a game like Unreal 2 at 1280x1024?

Right now it's hovering at about 114f when idling at the windows desktop, and at about 140f when looping the Unreal 2 intro demo. But in the latter state, the fan is noisier than I would like it.

1. Where on the motherboard is the temperature sampled from? Within the CPU, or somewhere outside of it?

Usually down in the middle of the socket, right beneath the chip.

Isn't the temperature sensor (diode) now embedded in the CPU core?

I would go to the motherboard monitor site and look at the motherboard list. If the cpu sensor listed for your board shows diode, then it is the internal diode.

Link

Oops. On newer chips, yeah. Most boards still have the sensor under the socket as well though.

114f seems a little high for an idle CPU, especially for an Intel. Even with the stock cooler, that temp shouldn't exceed 100f. (I only have experience with P4's up to 2.8, but I can't imagine that the 3.2 is THAT much hotter)

When stressed, the CPU could go up to 120-130f, but that's about all I would allow. I believe the max temp is about 160f for an Intel, and with your 140f you're getting pretty close to that.

Possible solutions :
Use a good high quality cooler, like the Zalman CNPS7000(AL)CU. They're really great coolers, and they're very quiet too.

Use good cooling paste, like Arctic Silver 3, not that crap that comes standard with the cooler. This can make a lot of difference.

Thirdly, you can also try to lower the voltage of your CPU just a little. If you don't exaggerate in this, your system will remain just as stable and the temperture will drop. Warning : this is a last-resort measure, and I would recommend to try the first to options first before doing this!

If all that doesn't give you the wanted results, you should look for alternative cooling methods like water cooling or phase-change.

I don't think I have ever had an Intel CPU that ran below about 110F, at least not since the early 386 days.

My current P4-2.4G idles at about 42C (114F). These are spec'd for proper operation up to 75C (180F), so you are well in the acceptable range.

Intel have a long and storied history of manufacturing space heaters.

Cheers

Yeah, 112 doesn't seem horribly bad to me. Before I replaced my faulty HSF unit on my AMD, it was running idle at around 50 degrees (C).

I second that Zalman unit. I've got it on my AMD and love it. It's nearly silent at low speeds that still cool it very well. The difference between low speed and high speed (which isn't very loud at all) is about 3-4 degrees.

112 *is* not that bad for an Intel, and it would actually be pretty cool if it were an AMD. (they run a lot hotter than Intel CPU's)
It's just that it could be cooler, that's all. And it WILL be cooler with such a Zalman fan. I absolutely LOVE those things!

Mark is right, Tony is not in the "danger-zone". But personally I would try and get those temps down a bit.

Yeah, I'm aware of all that, it was just that there seemed to be this opinion that it was too hot, when it doesn't seem too unreasonable for a stock cooling unit.

I believe the max temp is about 160f for an Intel, and with your 140f you're getting pretty close to that.

I read an article which showed that Intel's own built-in protection (the thing that'll slow down the CPU speed gradually based on temp if you enable the feature) kicks in around 172f. So yeah, I agree, I'd tend to want to keep it under 160.

Last night I tried putting in a makeshift duct which routed air from outside the case directly onto the CPU, then played a bunch of Unreal 2 with the case cover on. It worked great as far as keeping the CPU temp around 140f. And the motherboard temp didn't get above 115. So I was happy with that. Except then the problem became the disk drives. After that session, I opened the case and all the built up heat had made the drive casings hotter than I'd have liked. I'm going to investigate some case fans.

I also had another idea, that I could do a pairs of quiet 40mm fans in certain spots on the case that don't accept an 80mm fan. I remember seeing somewhere an ad for a very quiet 40mm fan, I'll see what I can come up with.

It shouldn't take much air movement to keep things cool in there.

The fans in my Empeg docks are 40x40x10mm, max 25CFM I believe, though I run them MUCH slower than that.

Cheers

I'll go with that approach for cooling.
Get a bigger fan with a speed control and slow it down until you get your personal balance between airflow and noise.
I have three 120 fans in my case, all slowed down to give my ears a rest.
Works quite well.

Last night I tried putting in a makeshift duct which routed air from outside the case directly onto the CPU...

A couple of months ago I was also looking for the ultimate cooling solution for my Pc. That's why I ended up with watercooling, but I did try it with multiple fans first.

I came to the conclusion that is was generally a better idea to remove heat by blowing the hot air out of the PC than by blowing room-temperature-air into the case.

I first tried this by making a smal tunnel through which the heat from the CPU was directly blown out of the case, so that it couldn't add to the temperature inside the case. I used those paper toilet rolls for that. Worked pretty well, but it could be improved.

I also had another idea, that I could do a pairs of quiet 40mm fans in certain spots on the case that don't accept an 80mm fan. I remember seeing somewhere an ad for a very quiet 40mm fan, I'll see what I can come up with.

I wouldn't do that if I were you. No matter how "quiet" these little fans are supposed to be, they will ALWAYS be more noisier than their bigger brothers. The reason is simple : a small fan has to rotate faster to move an equal amount of air as a larger fan, and thus tends to be noisier.
It's for this reason that I modded my case with a dremel tool so that 120mm fans would fit. The ideal setup is one 120mm fan on the front bottom of your case blowing fresh air into the case and one 120mm fan at the back pulling the hot air out. That way you get as sort of "continuous air flow" through your case. That, combined with a good CPU cooler will give you the best results.

Of course, not all case can be equiped with 120mm fans, not even after using a dremel tool on them. In that case I woud still advise you to use 80mm fans where possible, and avoid small fans as much as you can. Adding lots of little fans to your system WILL increase the noise it makes tremendously, even if they are so-called "silent fans".

I'll add a few pics of my setup to show you what I mean.


This is the backside of the case. You can clearly see the big 120mm hole that I made with the Demel tool. Through the hole you can see the other 120mm hole I made in the front of the case.


This is the big hole in the front of the case up close.

This is with the 120mm fan on. The fan is a Vantec "stealth" fan, supposed to be very quiet. (and it is). You can also see the pump and the reservoir of the water cooling system. The big black thing in the upper left corner is the radiator.

I'm very pleased with the result. The mod is invisible (because there's still a metal and a plexi plate with holes in it on the front of the PC) and performs very well. Also, because the fan is also behind the harddisk tray, my harddisk stays nice and cool.

used for second pic

used for third pic

I came to the conclusion that is was generally a better idea to remove heat by blowing the hot air out of the PC than by blowing room-temperature-air into the case.

Yeah, I agree that I need to work on doing that properly.

I first tried this by making a smal tunnel through which the heat from the CPU was directly blown out of the case, so that it couldn't add to the temperature inside the case.

I agree with this idea, but to do that I would need to reverse the direction of the Intel-supplied fan that sits atop the CPU. Its current design has it blowing downwards onto the heat sink. I wonder if there's a way I can just flip it?

I wouldn't do that if I were you. No matter how "quiet" these little fans are supposed to be, they will ALWAYS be more noisier than their bigger brothers. The reason is simple : a small fan has to rotate faster to move an equal amount of air as a larger fan, and thus tends to be noisier. It's for this reason that I modded my case with a dremel tool so that 120mm fans would fit.

Interesting! Definitely something to consider.

Marvelous pictures, thank you!

Keep in mind that fans blow more or less straight outwards, but they draw air more from a radius around the edges.. Inverting the fan direction on a CPU heatsink will likely make for decreased cooling.

Cheers

Good point. Since I can monitor the temp/fanspeed ratios, I could reverse it and try it to see if that's the case.

The fan is kind of "ducted" over the heatsink in this configuration, so maybe it will just be drawing from the heatsink as much as it would have been blowing on the heatsink.

There are some heatsinks that desire a certain direction of airflow - fan sucking or blowing. Some of the Alpha heatsinks want the fan to suck air instead of blowing air on the heatsink. I believe it had to do with having cooler air at the base of the fins instead of the tips.

My current P4-2.4G idles at about 42C (114F). These are spec'd for proper operation up to 75C (180F), so you are well in the acceptable range.

Sorry for the nitpick, but you need a new C->F conversion chart.

42 * (9/5) + 32 = 107.6
75 * (9/5) + 32 = 167

--John

Hmm, he's right. Mine's running at 144F, which the program converts into 46C.

So, congratulations! You've cooled your CPU without doing anything!

hmmmm... My PIV 3.0GHZ surfing the internet is at 36.3C or 97.3F

I'll add a few pics of my setup to show you what I mean.

I have a Lian-Li that looks just like that. Think I could yank a bunch of its fans and mod it to take some 120's? But I'm no longer a fan (no pun intended) of the Vantec Stealths; had a bad experience with them earlier this year.

Another note along those lines is that one fan blowing into or out of the case moves x amount of air. 2 fans blowing in or 2 blowing out moves nearly 2x as much air (small losses based on what the air flows over to get into the case and such. However, one fan blowing in, and one blowing out, only moves something like 1.5x as much air. It was always better having all fans going in, or out, of whatever chamber you were working with. This is from our lab tests in HVAC class, and generally agreed on by the prof.

Some things I've done if it gives you any ideas:
1) I have a single 90mm fan at the very front of the hard drive cage, with three drives installed in the cage. This works for the Antec case and anything similar, may or may not for you. I also have three hard drives in it, so... cools them quite well.
2) I have only two case fans, both in back blowing out. They are the Panaflo L1-A's. There's L1, M1, H1, and U1, each flows progressively more air. (I also theorize the letters stand for low, med, high, and ultra but haven't seen anything to back that up). The L1-A's blow "a good amount" of air, enough to keep my happy that the case has a constant flow through it, but I can't quantify that amount. These fans are 100% silent. OK, 99% anyways. I can't hear them. (Also, my power supply blows air out as well, and there's slats in the front of the case where it all draws in from. Makes neat dust patterns).
3) On the CPU cooler, I have a Thermalright AX-7 heatsink. I think the bigger the better. More fin, more surface, more heat loss. Their SK-900 and some others are supposed to be even better. I have a YS-Tech adjustable speed fan as well. Some may consider it a pain, and I guess I wish it was in fact automated, but what I do is turn it down to nearly silent for surfing, and up if gaming. With the speakers up or headphones on I can't hear it anyways.
4) I don't have a fancy clear window on the side of my case, so I went ahead and grabbed a piece of fuzzy carpet remnant from a friend who just built a house. I put a small piece under the power supply near the CPU, and a large piece that completely covers the side of the case above the CPU. (I did wash it and brush it to get as much fuzz as possible off - yes it looked silly but satisfied me I wouldn't mess anything up with stray fibers). This little mod made a huge difference on the amount of noise coming out of the case.
5) Lastly, as an Athlon owner, I don't monitor temps too much, I just know they run hot. The difference between 40 or 50, even 60 if an hour into a high paced game, means nothing to me. So what if the CPU lasts 20 years instead of 25? I don't see it worth being concerned about.

I'm not sure. What Lian-Li case is it? My case is not a Lian-Li case. It's an AMS gTower case. I deliberately stayed away from Lian-Li because they almost all (well, the midi tower series anyway) use such a "pull-out" system, with which you can pull your whole backplate out via the back of the case, when your motherboard is still screwed down. (sorry, don't know how else to describe it, but you probably know what I mean). This results in a Lian-Li only using one or two 80mm fans rather than 120mm. I doubt they have the room to mod it for use with 120mm fans.

I must admit that I gathered all my information concerning this from photos I saw of Lian-Li cases. I didn't go and measure up one of those cases IRL. So it might be do-able, but if it would fit, I imagine it would be *really* tight.

One place I'm almost 100% sure you CAN mod a hole into is in the top of the case. This helps extremely well to pull the hot air out, as hot air rises anyway.

Concerning the Vantec fans, I happen to agree with you. Considering all the trouble I went through to actually lay my hands on them (they weren't available in Belgium at the time), I now know that they weren't worth it. They do the job for now, but if I had to make a new choice at this time I would definitely go for Pabst fans, or maybe Enermax.

I went ahead and grabbed a piece of fuzzy carpet remnant from a friend who just built a house. I put a small piece under the power supply near the CPU, and a large piece that completely covers the side of the case above the CPU. (I did wash it and brush it to get as much fuzz as possible off - yes it looked silly but satisfied me I wouldn't mess anything up with stray fibers). This little mod made a huge difference on the amount of noise coming out of the case

I too did this once. Except I bought some specially designed Pax carpets to quiet the case. And I must admit : it helped. The only downside was : the temp in my case got A LOT higher from then on. I realised then that the carpet kept the case from loosing at lot of it's heat through natural convection.

It's because of this that I would not recommed such acoustic mats. To get your system quiet, it's better to invest in quiet fans and HD enclosures IMHO.

I found that out as well when I tried to quieten a Shuttle SV-25. The acoustic mat reduced the noise a little but it got very hot inside due to the insulation effects of the foam. Also it really smelt and even after a few months it still had a lingering plastic/petroleum odour to it.
It's quite difficult to get the stuff off as well I found!

In the end I replaced the CPU heatsink/fan, PSU fan and casing fans and it's much better now. I wouldn't want it in my bedroom but it's okay under my desk.

I deliberately stayed away from Lian-Li because they almost all (well, the midi tower series anyway) use such a "pull-out" system, with which you can pull your whole backplate out via the back of the case, when your motherboard is still screwed down.

Although both side walls and the front plate are easily removable, the motherboard tray is only removable (from the side) after removing a screw or two.

One place I'm almost 100% sure you CAN mod a hole into is in the top of the case.

This particular case already has a ceiling fan blowing out. It also has two fans on the front wall that pull air in, and yet another case fan on the rear. Also, my Enermax PSU has a fan on its bottom (inside the case) as well as on the back.

So, if I can't fit a 120 in the front, I think I should probably be able to at least swap out the two fans that are there for a 92. And since the rear of the case looks IMHO exactly like yours, I think I can put a 120 there. As for the ceiling, if I can squeeze a 92 up there (assuming that's what the current one isn't), I'd be happy. Do you think that might be one fan too many?

My P4 2.26 using the stock Shuttle ICE heatpipe sits about 46 when idle with the fan at quiet speeds, and it drops to 38 with the fan running full blast. Under load, CPU usually sits in the 50's. 68 is my threshold for the fan to kick into full speed mode, and it has never done this on its own.

--edit And for the record, all P4 chips have had integrated diodes to measure their temp. This is how they implement the emergancy clock throttling if the processor overheats. Athlons, the initial ones didn't have a diode, but the recent ones do (Athlon XP, etc...).