Sensor Locations on B75M DGS R2.0 Motherboard?
Printed From: ASRock.com
Category: Technical Support
Forum Name: Intel Motherboards
Forum Description: Question about ASRock Intel Motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=2336
Printed Date: 29 Dec 2024 at 4:16pm
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Topic: Sensor Locations on B75M DGS R2.0 Motherboard?
Posted By: gustavio
Subject: Sensor Locations on B75M DGS R2.0 Motherboard?
Date Posted: 30 Mar 2016 at 8:18pm
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Hello all, Does anyone know where the CPU and Motherboard (chassis) sensors are located on the B75M DGS R2.0 motherboard? Any help in identifying the locations would be greatly appreciated. I have attached two pictures for your reference: Thank you, gustavio   |
Replies:
Posted By: gustavio
Date Posted: 31 Mar 2016 at 5:15am
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Hello all (again), Maybe I was asking for too much information in my previous post so I'll refine it down to a more simple request but first I'll explain why I am seeking the refined information. Ok, so I did some cable management in preparation for the installation of a new PCI-E card: Before the cable management, my chassis temp was usually about 2c lower than my CPU temp. After the cable management rearrangement, my chassis temp is now about 3-4c higher than my CPU temp. These Speccy readings are same as reported by my ASRock BIOS. The Speccy cpusocket reading matches the chassis reading in my ASRock BIOS. Right now my ambient is about 21c and here are the Speccy readings:  So, it seems like I changed the airflow somehow and I would like to know where the chassis sensor is physically located. And, I would also like to know if the chassis temp is also referred to as the cpusocket temp. Thanks for your help, gustavio |
Posted By: parsec
Date Posted: 31 Mar 2016 at 7:40am
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The single "mother board" temperature sensor location is one of the great mysteries of any mother board. Mother board manufactures have given us this lone temperature reading for many years, without explaining what significance it has. I am not aware of any mother board's manual or monitoring program that gives the location of the single "mother board" temperature sensor on their products. That includes your board, I have no idea where it is, or where it is on any of the mother boards I use now or in the past. There are a few boards such as the ASRock OC Formula series that have multiple (~10) temperature sensors located at various places on the board. The monitoring program ASRock provides for these boards has a display that shows the location of the sensors, and their temperature readings. This display does not include the "mother board" temperature. Once you use a mother board like those I described above (which I have), you understand that the value of one mother board temperature reading is small. Add to that the unknown location of that sensor, and its value becomes even less IMO. You referred to the mother board temperature sensor as a "chassis" sensor, which is confusing. Usually the PC's chassis is the PC case that contains all the parts of a PC. The term "chassis fans" normally mean fans mounted on the PC case, and the "chassis fan" headers on a mother board are the connections we can use with those fans. Where do you see anything labeled as a "chassis" temperature? Intel and AMD have different ways of providing CPU temperature data, and I'll only be talking about Intel's methods here. An Intel processor has multiple temperature sensors built into it, and the methods for reading that data are provided by Intel. We normally have a temperature for each processor core in the CPU. Your Pentium G2020 has two cores, and it should provide two core temperature readings. An Intel processor may also provide a "package" temperature, as well as a "graphics core" temperature. These sensors are also part of the processor itself, they are not sensors added by the mother board manufacture. If an Intel mother board has an added CPU socket temperature sensor, its value is questionable, since Intel uses the internal sensors it built into the processor to determine if it is over heating and should be shut off to prevent damage. A socket temperature sensor reading will likely be less than the true internal temperature of the processor, and really provides little useful information. Mother board monitoring programs like Speccy are designed to work with all the different mother boards that we may be using, as well as being made for Intel or AMD processors. That is a difficult task, since all mother boards are not the same, and there are few standards about what sensor reading belongs to which sensor. Speccy is very generic and simple with its temperature readings. Its "Motherboard (CPUSocket)" reading has two different terms combined into one, which IMO does not make sense. AMD boards tend to have a CPU Socket temperature reading, but it certainly is not the mother board temperature. Matching temperature values as you did is the only way to know what the Speccy reading really is. The only value I find in the single mother board temperature is if it changes significantly or reaches 30C. ------------- http://valid.x86.fr/48rujh" rel="nofollow"> 
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Posted By: gustavio
Date Posted: 31 Mar 2016 at 8:35am
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Wow parsec! Thank you for that detailed explanation! It was very well written and quite informative to say the least. The reason I used the term "chassis" is because that is the way it is identified in the ASRock BIOS:  So, I thought maybe the terms "chassis" and "CPUSocket" might be somewhat interchangeable because the readings matched... but I guess not. Again, thank you so much for your detailed explanation. Best regards, gustavio |
Posted By: gustavio
Date Posted: 31 Mar 2016 at 10:32am
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Hi again parsec! Well I think I figured it out! So, after going over what I did and then reading your summary, I remembered that I moved my only chassis fan connection from a molex power connector to the actual chassis fan connection on the motherboard; however, since this fan has a 3-speed switch, I left the 4th wire off as I didn't want the mobo to try and regulate the fan speed. Now I can see that constant fan speed in the BIOS; whereas, I couldn't see it before. So is it possible the motherboard is now reporting an actual reading from this chassis fan; whereas, it couldn't before because it was connected to a molex power source? Anyway, I'll prove it for sure when I install my new PCI-e card on Saturday and report back. Again, many thanks for you detailed response. Best regards, gustavio
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Posted By: parsec
Date Posted: 31 Mar 2016 at 11:19am
Gustavio, you got me with the "chassis" temperature sensing in the manual!  I still think that is not a good name for it, but what do I know?  I can tell you that if you have any fan connected to a molex power connector, you won't see the fan's speed in the BIOS or anywhere else. A molex connector only has +12V and +5V power wires in it, and the two ground/earth wires for each voltage. That molex cable is from the power supply, which has no method of sending fan speed data to anything. A PC fan with three or four wires uses the yellow wire as the fan speed/RPM signal wire. The fan speed/RPM signal must be somehow connected to the mother board through a fan connector on the board so the speed can be shown in the BIOS or in a hardware monitoring program. You can get a molex fan power adapter that has an extra three pin fan connector on it, with one yellow wire that you can connect to a mother board fan connector, so you can see the fan's speed. Using the fan connector on the mother board lets you control the speed of your fans. The fan speed control setting in the BIOS is probably not set on full speed, so that fan is now spinning slower than it was when it was connected to the molex connector. That could explain why the mother board temperature went up a little bit, because the fan is now spinning slower. Can you hear the difference in the fan's speed? Get into the BIOS and check the speed setting for that fan. You should be able to change it to be faster, which would reduce the mother board temperature. Or if you can put more fans in your PC case, that might help too. ------------- http://valid.x86.fr/48rujh" rel="nofollow">
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Posted By: gustavio
Date Posted: 31 Mar 2016 at 11:41am
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Hey again parsec, Here's my responses to you last post (line by line): I still think that is not a good name for it, but what do I know?  [Agreed] I can tell you that if you have any fan connected to a molex power connector, you won't see the fan's speed in the BIOS or anywhere else. [Understood] A molex connector only has +12V and +5V power wires in it, and the two ground/earth wires for each voltage. That molex cable is from the power supply, which has no method of sending fan speed data to anything. [Understood] A PC fan with three or four wires uses the yellow wire as the fan speed/RPM signal wire. The fan speed/RPM signal must be somehow connected to the mother board through a fan connector on the board so the speed can be shown in the BIOS or in a hardware monitoring program. [Yes, it is connected. I have a 3 wire connection to the chassis fan connection on the mobo] You can get a molex fan power adapter that has an extra three pin fan connector on it, with one yellow wire that you can connect to a mother board fan connector, so you can see the fan's speed. [Don't need it but I think you already answered my question above] Using the fan connector on the mother board lets you control the speed of your fans. [I think you need the 4th wire connected to control the fan speed; however, since my fan has a 3 speed switch, I control it manually by choice] The fan speed control setting in the BIOS is probably not set on full speed, so that fan is now spinning slower than it was when it was connected to the molex connector. [Not in this case, the speed is manually controlled by a 3 speed switch. The speed is exactly the same as it was when connected to the molex (1,500 RPM); however, the reporting wire is now connected to the mobo] That could explain why the mother board temperature went up a little bit, because the fan is now spinning slower. Can you hear the difference in the fan's speed? [No speed change but that 3rd wire may now be reporting temperature sensing now that it is connected to the mobo and the previous readings may have been bogus due to a lack of reporting. Maybe now I'm just seeing a true reading?] Get into the BIOS and check the speed setting for that fan. You should be able to change it to be faster, which would reduce the mother board temperature. Or if you can put more fans in your PC case, that might help too. [The fan speed regulator wire is not connected to the mobo but the reporting wire is connected. I think the reading might be coming from a sensor on the fan and getting reported back to the mobo] [Right now, I'm OK with the temps and since my PC is dead silent, I don't think I'll change anything right now.] Thanks for all your help too! Best regards, gustavio
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Posted By: gustavio
Date Posted: 31 Mar 2016 at 11:15pm
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Hello again parsec! Well, I moved the chassis fan back to a molex connection and there was no change in that (unknown) temperature reading. Anyway, my CPU and SSD are idling at 2-3c above ambient. The max load temps are great as well. In fact, I have yet to see my CPU hit 40c. FYI, I am not a gamer but I do a fair amount of mediocre graphics rendering. So, at this point, I think I'm going to leave well-enough alone because I think this unknown temperature reading falls into the category you previously described in one of your quotes as follows: "Once you use a mother board like those I described above (which I have), you understand that the value of one mother board temperature reading is small. Add to that the unknown location of that sensor, and its value becomes even less IMO." Thanks a bunch for all your help! gustavio |