"Acceptable" CPU Temps?

[Twiggy]

*Decided to post here because this should, I think, apply to any computer, not just Thinkpads*

I have owned a Thinkpad T42 for about the past two months, and it's great. Only complaint I have about it, is that the fan is rather loud, and I found out that it's normal for Thinkpad's of it's age and series to have a lot of fan noise, because the BIOS fan controller makes the fan go much faster than it needs to be most times.

Because of this someone made a program called TP Fan Control, where you can control fan speed from Windows (XP in my case).

I just tried using it, and while playing Old School Runesape (which is the main reason I bought the T42) if I set it to use the BIOS controller the noise sounds as usual, if I use the "smart" option, it sounds the same as with the BIOS option, and the speed is almost exactly the same too (rpm).

However it does also let you enter fixed speeds from 0-7 (0 being fan off, 7 being almost as fast as it can go, and then there's "64" which is truly as fast it can go).

When I have it at 3, the amount of noise sounds the same, but when I turn it down to 2, it is near silent.

It also tells you the CPU temp, and with a fixed speed of "2" I am not seeing higher than 78c, though with BIOS I am seeing 73-75c.

A friend of mine says that Ideal CPU temp is 73c or less, but up to 75c is fine. However my desktop which is running an i7-4790k 4ghz, is usually in the low-mid 80's, and I once saw it under a stress test get to 88c, and it's worked no problem for well over a year since I installed it.

From what I understand if it's running a bit above 75c then, it will still work, but just not last as long as if it was lower.

So I take it that as long as it's not going much above 80c, it's not ideal but would still be "acceptable"?

I mean I've heard that sometimes some CPUs in macs get up to 90, or even 100c.

Of course I don't know much about temps, which is why I am asking.

[axur-delmeria]

My personal creed is "the lower the better". High temperatures shorten the lifespan of electronics, so it's worthwhile to make the effort to lower them. Undervolting the CPU yields some benefits.

It's been a long time since i've used a T42 so I don't have a detailed memory of the temperature range, but I don't remember the CPU ever reaching 80c.

Another concern is the Radeon GPU. Some T42's have the short heatsink where only the processor was covered. IIRC the old timers here generally recommend the longer heatsink that also covers the GPU.

The i7-4790K is saddled with high temperatures due to having thermal paste between the bare silicon die and the heat spreader (Intel going cheapskate to increase their profit margin). In older processors, the heatspreader is soldered to the silicon die resulting in better thermal conductivity. That's why oveclockers delidded them to replace the paste with better stuff like liquid metal, resulting in a temperature reduction of at least 10c.

[theterminator93]

I don't know if I've seen good data for this (to be fair, I haven't spent a ton of time looking ) but the lower the better is always a good place to start.

It's hard to give a hard number that spans CPU generations because each has its own set of quirks. Higher clock speeds at full power always generate more heat than the CPU of the same generation that isn't capable of running as fast. E.g. a Sandy Bridge with a max turbo of 3.3 GHz, running at that speed, will put out more heat than a Sandy Bridge with a max turbo of 2.9 GHz, running at that speed. And newer CPUs tend to run at high clock rates, owing to the improved efficiency of the desigh. This has them offsetting the higher clock speeds and lower power for smaller heat sinks, thinner designs, and roughly the same temperatures at load. That said just about all modern CPUs will run as hot and fast as they can until they reach a thermal limit, which is often somewhere in the low 90s.

Personally, and this is with my Sandy Bridge systems (X220, T420, W520), I don't like to see temps above 60 for light use. 65-70 is about what I expect for occasional periods of stress with CPU utilization going up and down. When I have one core pegged, I expect mid-70s, maybe uppper if the ambient temp is higher than usual. And if all cores are pegged, mid-upper 80s IME is typical. Again the better the cooling, the higher the CPU can throttle itself.

With my undervolted T9900 T601F, I rarely see temps above 65 for normal use. With both CPUs pegged it will get into the low-mid 70s. Every system has its own personality. Take some time to get to know yours so the expectations you are setting are realistic. You can control it to a degree by using good thermal paste, keeping the heat sink and fan clean, and controlling fan and clock speeds/voltage (where feasible).

Maybe later I can break out my T42p and do some testing. It's been a while since I've played with it...

[Droider]

Hi,

You need to specify the cpu model in your T42 because just saying T42 isn't enough. Apply some quality thermal paste to cpu and replace fan assembly if your t42 has the short fan which doesn't make contact with radeon7500 chip.

This is my observation of T42 with various cpu's, they are ideal.
CPU / IDLE / LOAD
1.7ghz / 50 / 70
1.8ghz / 50 / 70
2.0ghz / 55-58 / 75-78

[Twiggy]

Pentium M 755 2.0Ghz

I have some new internal parts coming in soon, so I will take a closer look at the heatsink/fan and maybe clean it out thoroughly soon, as well.

[kfzhu1229]

"Acceptable" CPU temps are higher on laptops (and especially ultrabooks) than desktops generally speaking.
For a ThinkPad of this age though, I would say keep it under 85C. If my T43p with a heat-ier PM780 and V3200 can do it with some undervolting, so can you.
As for the noise, I never find any of the T41 T42 fans to be any loud at all especially compared to the T43/p fans (The only laptop with a quieter fan than those in this era that I have is a Latitude D610 but that is also having separate large GPU heatsink block than the CPU).
If you think it is loud, try to describe the kind of loud that you hear it from. If you hear noises like grinding noises and the fan getting noisier when you tilt the laptop back and fourth, you might need to lubricate the bearings on that fan before it throws you a fan error and die completely. That will involve with separating joints between the copper plate on top and the aluminium fan bracket, and typically only T43/p fans need this since they spin faster and the bearings dry out faster, but I did have to do one to a T42, and it gives you much more freedom in cleaning the heatsink properly from the inside.

[Twiggy]

I just ran a Prime95 CPU stress test for about an hour, and it went up to 78c (when using BIOS controlled fan speed), then just a minute after I stopped it, it dropped down to 60c, and not long ater that, went to 54c. So I guess that 78c after one hour of an unrealistic stress test, is not bad at all.

I now need to try it with fixed fan speed of "2".

I am should have a new ram module in soon, so considering the fact I will need to inside the machine again, I will take a look at cleaning out the fan/heatsink more properly as well when that happens.