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Safe CPU Temp

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August 14, 2006 5:32:32 AM

Hello Everyone,

First, long time Tom's reader, but first time poster. I was just wondering about what the idle Temp is for a 940 DC 3.2GHz CPU. I just put my new system together and ran it last night just in the BIOS, and noticed the CPU Temp stabilize @ around 59 degrees celcius. I was just wondering if this is a normal temp, or if this is too high. I've tried searching the forums for an answer but can't seem to find anything, so if there is one, feel free to direct me there instead.

I'm using an Asus P5B MoBo, 940 Chip, with a Zalman CNPS7000 ALCu cooler, using the ZMCS1 bracket for 775. It's all in a Termaltake Swing Case, and I've got a front Intake and Rear exhaust fan in the chassis.

The Thermal paste should be ok, I didn't layer it on, but it's not too thin either, and the MoBo temp sits at around 29 degrees C.

Thanks

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August 14, 2006 5:44:03 AM

I just helped someone on thins exact issue, except it was an OC'd 805. Consider yourself lucky. :wink:

http://processorfinder.intel.com/Details.aspx?sSpec=SL94Q
Thermal Specification for a stepping B1 stock 940 is 68.6C.

Quote:
Thermal Specification: (Also referred to as Thermal Temp) The Thermal Specification is the temperature at the critical point on the die and usually represents the hottest point on the processor. Therefore, the Thermal Specification represents the maximum temperature for reliable operation of the processor.

Your temps are within spec, but I think they're still pretty high. Reduce them if you can.

========================

Remember people: Intel is your FRIEND. If you ever need to check the max thermal spec for your Pentium D, go here:
Pentium D Index Then, click "View Specification Chart," then click the sSpec number (the column farthest to the right) that applies to your processor. In this person's case, the sSpec was SL94Q.
August 14, 2006 5:45:56 AM

That sounds quite high considering the case temp is 29C. That is 59C at idle or at full load?

If its 59C at idle then you have a problem. I would make sure that all the clips on your HSF are totally in securely. If that doesn't help then.. ouch, someone with more experience than I may need to suggest something but I would say your CPU is somehow damaged or the fan on the HSF is not working...(do make sure the fan is spinning)

If its running at 59C full load thats not too too bad, but still seems high, maybe if you let the thermal paste cure it will go down a little.
Related resources
August 14, 2006 5:54:29 AM

Try checking the temp when you have the OS installed.
a b à CPUs
August 14, 2006 6:05:09 AM

Quote:
Hello Everyone,

First, long time Tom's reader, but first time poster. I was just wondering about what the idle Temp is for a 940 DC 3.2GHz CPU. I just put my new system together and ran it last night just in the BIOS, and noticed the CPU Temp stabilize @ around 59 degrees celcius. I was just wondering if this is a normal temp, or if this is too high. I've tried searching the forums for an answer but can't seem to find anything, so if there is one, feel free to direct me there instead.

I'm using an Asus P5B MoBo, 940 Chip, with a Zalman CNPS7000 ALCu cooler, using the ZMCS1 bracket for 775. It's all in a Termaltake Swing Case, and I've got a front Intake and Rear exhaust fan in the chassis.

The Thermal paste should be ok, I didn't layer it on, but it's not too thin either, and the MoBo temp sits at around 29 degrees C.

Thanks


Check the Vcore voltage.
August 14, 2006 6:19:56 AM

Jumpjack: what cases where those (Just curious).
August 14, 2006 7:27:38 AM

If you want to see the idle temp, you must do it on windows desktop not in the BIOS. In BIOS it will be higher but 59 C is too high. Therefore, you have a problem. Try to reseat the cooler and see if there is a difference. Be sure to apply a thin layer of thermal paste (Arctic Silver 5 is the best). To remove the old thermal paste you can use ArctiClean. Verify that all the clips on the heatsink are totally in secure.
August 14, 2006 5:57:01 PM

Quote:
What case --- I have a 3.6 GHz preshott and it idled at 48 deg C and went to 62-65 under load. I am using a Asus MB (older version), zalman fan all Cu.

I switched cases this weekend and dropped from 45-48 deg C or so to 35-38 deg C Idle and 55 deg C under load. Made a huge difference.

Jack


You don't truly believe that do you Jack ???

Especially considering his mobo temp (which is greatly affected by case temp) is only 29C , I would say his casing (therefore his case temp) is just a-ok.

Maybe its just your reapplication of the HSF compound that did the trick. Did you truly transfer "everything" intact into the new case (so that ONLY the case is the contributing factor in the equation) ??
Don't think so.
August 14, 2006 5:59:41 PM

Thanks for the info everyone,

Here's what I've done, I removed the Zalman 7000 Heatsink, and noticed that one corner of the heatsink barely touched the CPU since it had little or no Thermal Paste stuck on it. I re-applied the Thermal Paste (BTW I'm using the Paste Provided by Zalman in the little tubes) and checked to make sure the Heatsink is secured to the CPU. I currently have no OS loaded and am just checking the Hardware Monitor in BIOS, here's what it comes up with:

CPU Temp: Hovers at around 58.5C-61C
MoBo Temp : Hovers at around 35C - 39C
CPU Fan: 2250 RPM
Fan 1 (Rear): 2600RPM
Fan 2 (Front): 2600RPM
VCore: 1.176
3.3V: 3.248V
5V: 5.145V
12V: 12.144V

The Zalman cooler is connected through their Fan Mate 2, and it's cranked to MAX, though I think the RPM's are a little low considering Zalman says it can run to 2600 RPM.
The 2 Case Fans are both Thermaltake Smart Fans 120 x 120.
I even tried changing the rear Fan around so that it would blow in instead of suck out, but little or no difference.
The Power Supply is an Enermax VP495 485W.

Based on the SPECS from Intel (Thanks for the Link MEX) it seems ok, but it just seems to high to my liking!!
August 14, 2006 6:08:41 PM

According to zalmans website the Zalman 7000CU and 7000 ALCU both are rated for 2,600 rpm fan speed (just something I wanted to point out).

There is no way that this temp is because you're using the paste that came with the cooler. Arctic silver does work better IMO, but thermal paste would definetly not allow something like this to happen unless you applied it very wrong.

The core voltage seems really low, its suppose to be 1.25V-1.4V according to that sSpec. This leads me to think maybe the sensors on the motherboard are wrong.

Thats just a theory... but if those temps are real I would be worried since 58C in the BIOS is way too high. That means when you actually use the CPU at full load your probably cooking that thing at 68C+ which is the thermal limit according to the Sspec.
a b à CPUs
August 14, 2006 6:21:37 PM

Quote:
According to zalmans website the Zalman 7000CU and 7000 ALCU both are rated for 2,600 rpm fan speed (just something I wanted to point out).

There is no way that this temp is because you're using the paste that came with the cooler. Arctic silver does work better IMO, but thermal paste would definetly not allow something like this to happen unless you applied it very wrong.

The core voltage seems really low, its suppose to be 1.25V-1.4V according to that sSpec. This leads me to think maybe the sensors on the motherboard are wrong.

Thats just a theory... but if those temps are real I would be worried since 58C in the BIOS is way too high. That means when you actually use the CPU at full load your probably cooking that thing at 68C+ which is the thermal limit according to the Sspec.


You make some great observations. If the 58c idle temps is right in BIOS, and I suspect it's close, and the low voltage to the Vcore is correct, which I suspect is correct...I would get a different (more powerful/stable) power supply. It has been my experience to upgrade to a dual 12v rail 500 to 550 watt or more to attain better stability and correct voltages. Also, Jack hit on the better case with better airflow. That is my experience also. In addition, you didn't mention your othet components. For example a powerful video card creates a lot of heat (turn the exhaust fan back the way you had it, exhaust.) Also RAM generates a lot of heat, especially if you are using 4 dimms.

I would consider getting a 550 watt dual 12v rail PSU in there. With that Zalman your temps are too high.
August 14, 2006 6:35:10 PM

I seriously doubt he needs a better power source. Enermax makes good power supplies and 485 watts should be plenty, especially when just booting up and such.

I would like someone with more experience/knowledge than me to make validate this assumption but I believe it may be a bad CPU or motherboard. Either the CPU is damaged (hence the high temps and low voltage input) or the motherboard is somehow damaged (hence the bad sensor and inability to supply correct voltage).

And do make sure the fan in the back is exhaust. Feel that air when you use your computer. Does it feel like the CPU is really running at ~60C? I'm not sure if people can tell the difference but just by feeling the air coming out of the back I can tell the difference between 40C and 60C air.

I don't really recommend this, but I sometimes touch the heatsink to see if it is really hot or not, but i'm not sure if static electricity would be an issue there (I do stupid stuff to my comp all the time but it has never failed me yet).

In other words the main thing we need to see is if the sensor is correct.

Side note: Will a Pentium D 940 boot at 1.176 volts??
a b à CPUs
August 14, 2006 6:42:11 PM

Quote:
I seriously doubt he needs a better power source. Enermax makes good power supplies and 485 watts should be plenty, especially when just booting up and such.

I would like someone with more experience/knowledge than me to make validate this assumption but I believe it may be a bad CPU or motherboard. Either the CPU is damaged (hence the high temps and low voltage input) or the motherboard is somehow damaged (hence the bad sensor and inability to supply correct voltage).

And do make sure the fan in the back is exhaust. Feel that air when you use your computer. Does it feel like the CPU is really running at ~60C? I'm not sure if people can tell the difference but just by feeling the air coming out of the back I can tell the difference between 40C and 60C air.

I don't really recommend this, but I sometimes touch the heatsink to see if it is really hot or not, but i'm not sure if static electricity would be an issue there (I do stupid stuff to my comp all the time but it has never failed me yet).

In other words the main thing we need to see is if the sensor is correct.

Side note: Will a Pentium D 940 boot at 1.176 volts??


Silverstar, you do have the 12v plugged into the MB supplying power to the CPU, right. Also, my ASUS board in my sig has an additional 12v plug to the MB. I suspect you have these plugged in.

AOOBOB: I am using a five year old Enermax 485 watt PSU on the computer I'm typing on. Excelent over the years, but getting a bit of fluxuation these days. I have a brand new Enermax 535 SLI sitting in an unopened box as a back up. Could be the MB voltage regulator is defetive.
August 14, 2006 8:43:39 PM

Here's my full list of parts.
Asus P5B
OCZ Dual Channel 533, 1GB, both having heathshields
Pentium 940, 3.2GHz
ATI X800XL PCIE
Pioneer DVR 111
Maxtor SATA2 250GB
Zalman CNPS7000 AlCu LED Cooler
Two Thermaltake 12Cm x 12 cm Rear and Front Case Fans
Enermax 485W EG-495P-VE SFMA
Thermaltake VBS6000SWS Swing Case

At this point, having put everything together, the only thing I've done is turn the system on just to load it into BIOS to check the CPU Temp.

The Enermax PS has dual 12V rails, and yes I've plugged the 24 Pin 12V Connector for the MoBo on the right hand side, as well as the 4 Pin CPU 12V connector just to the top left of the CPU on the MoBo.

I'm thinking my next step at this point is to remove the Zalman cooler and try the stock Intel Cooler still in the Chips box, I wasn't planning on using it, but I guess I should see if it's the cooler. The only reason I say it maybe the cooler is because Zalman doesn't have any ratings on this cooler for a Pentium D. Zalman only says it can be used on socket 775, as long as you get the ZM-CS1 bracket, but there's no info on what 775 chips it supports.

AODBOB, the air coming out from the rear exhaust fan feels no where close to 60C, it doesn't even feel close to 30C, and there's A LOT of air moving out the back. With the design of the case, because the HDD Cage sits right in behind the front fan, not as much air moves from the front to the MoBo back, but you can feel it. The exhaust fan from the PSU is barely noticeable compared to the Rear Case Fan itself. I also did try touching the Heatsink, but only after I powered down the system and let it sit for about maybe 3 - 5 mins, and the Heatsink fins are warm, maybe close to 30C - 40C, but nothing Hot.

I have a friend who has an overclocked 930 chip and he says his CPU at idle sits at 30C - 50C, but he will confirm to me when he gets home.

I have another friend who uses an 800 series Dual Core at her work system and she'll try to check her BIOS temp
August 14, 2006 9:36:28 PM

I guess it won't hurt to switch out the heat sink fan and try it, but I doubt that will do anything ... more likely, it'll run hotter. That Zalman is a good cooler. It worked great for older P4s, it should be great for your 940.

Maybe the problem is related to how your thermal paste is applied?

Could you describe the method you used to apply the thermal paste to your CPU and heatsink?

Too much paste is not good, you know.
August 14, 2006 9:50:49 PM

Quote:
Maybe the problem is related to how your thermal paste is applied?

Could you describe the method you used to apply the thermal paste to your CPU and heatsink?

Too much paste is not good, you know.


Zalman gives these very small tubes of paste with their cooler, probably enough for one and a half pea sized globs. I probably used a pea sized amount about 70 - 80% of the tube. I have a small plastic puddy knife (completely clean, never used for anyting) and spread it around, it's not thick at all, probably as thin as a piece of paper. I made sure to cover the entire metal surface inside the retaining bracket evenly.

Basically IMHO, the thickness looks close enough to the thickness of the pre-applied paste on the stock Intel Cooler.
October 7, 2009 9:03:06 PM

Hi All,

I too use to experience far high temps with the new i5 cpu (in excess of 70c+) when only on idle.

I found the problem to be due to the heatsink not correctly attached to the motherboard. Im using the Arctic Freezer Pro rev2 with Antec Silver 5 thermal compund. My particular heatsink lifted after being fitting due to the cheap plastic pin not correctly going into the motherboard holes.

Anyway after removing, repasting and correctly fiiting my idle temp has dropped from over 70c down to a much more respectable 38c! (for info my ambient room temp is 24c) . Also, my PC now runs quicker too.


For those of you experience very high idle temps, id advise checking that your heatsink is 100% properly fitted to the board and touching the cpu.

regards,
PK

ps - I have bog standard case with intake, side and exhaust fans - nothing fancy. If you have a Gigabyte motherboard dont be fooled by the low temps it shows you with the Easy Tune application - its wrong!
October 7, 2009 10:04:51 PM

I just posted essentially the same thing. Here are my results.

http://www.tomshardware.com/forum/267931-28-pentium-temps

940 D
955x Intel MB
2GB
EVGA 9800 GTX+

Arctic Silver 5 - very thin layer base, very thin line on cores and shifted heat sink to set in.
Cooled with Thermaltake's Big Typhoon.

CPU Idle: 36C at room temp
CPU Load: 42-46c with one Win XP VPC running Diablo 2 (which bakes the CPU)
EVGA Idle: 33c at room temp
EVGA Load: 42-44C

MB Idle: 32C

Will update after paste burn-in is complete in a few weeks.


!