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Dell fan speed control
I don't know if anyone knows, but I'd like to.
On the "classic" Dell systems that actually had parts inside that were designed and maybe even assembled by Dell, there is clearly some type of fan monitoring that is done by the BIOS. If you pull the plug on a fan, the system will beep unhappily and tell you at POST that a fan is not responding. I've looked at a dead Dimension E521 board to see how they might do this, as looking with software such as SpeedFan shows nothing. I found that this is because the LPCIO simply doesn't have any fan speed reporting, temperature reporting or fan control functionality. (Someone thought of using at least temperature reporting for the E521--there are unpopulated spots on the board clearly labeled as places for thermal sensors.) This is true of other Dell systems, such as the Dim8400, 8300, 2400 and OptiPlex 170. (Systems like the Dimension 2100 and its siblings (L5xx series) have temperature/fan monitoring functions in their LPCIO ICs, but it isn't used or connected.) I could not trace the board--it has too many layers. The mechanism for actual fan speed control is obvious--a temperature sensor bulb that protrudes into the airflow from the fan will speed it up if it gets hot. I'd like to know how Dell does fan speed monitoring, and while I suspect that this may require asking a Dell system board designer how it was done, I'm hoping that someone on the group might know. William |
#2
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Dell fan speed control
William,
Your question was, is, and will be actually a 2-part question. Dell used/uses a lot of Intel-designed motherboards. In the past, many of them have actually been identical to Intel's own designs, at least, superficially. Others are minor modifications to Intel designs. For the Intel boards in the Dells, the trend is obvious. Intel once had very nice monitoring software that ren only on 800-series chipsets and systems with an original generic Intel BIOS (not an OEM BIOS like Dell's or Gateway's). No longer does Intel provide monitoring software, and they apparently use for controlling fan RPMs a low-level scheme something that Speedfan et al cannot detect. For these Intel designed boards, I will claim that Dell provides exactly zero electronic design engineering expertise, only very minor variations in board layout and (rarely these days) cost-tradeoff discussions with Intel whether or not to drop board features. (Sometimes, it costs more to drop a feature during manufacturing than to keep it there disabled.) So for Dell boards with Intel designs, someone from Intel is best equipped to answer your question. For the non-Intel boards, the other board manufacturers themselves are better equipped to answer your question. I would be dumbfounded if Dell's "engineering" contribution to the design and manufacture of motherboards was much more than I have described above. The industry has matured to the point where motherboard designs are very much standardized, as is the manufacturing. There is little or no reason for Dell, HPaq, Lenovo, Gateway and the rest to have highly paid board designers in house for desktop boards. Instead, that expertise lies within Intel, Foxconn (actual mfr of Intel designs), Asus, etc... Ben Myers On Sat, 04 Oct 2008 05:01:21 GMT, "William R. Walsh" m wrote: I don't know if anyone knows, but I'd like to. On the "classic" Dell systems that actually had parts inside that were designed and maybe even assembled by Dell, there is clearly some type of fan monitoring that is done by the BIOS. If you pull the plug on a fan, the system will beep unhappily and tell you at POST that a fan is not responding. I've looked at a dead Dimension E521 board to see how they might do this, as looking with software such as SpeedFan shows nothing. I found that this is because the LPCIO simply doesn't have any fan speed reporting, temperature reporting or fan control functionality. (Someone thought of using at least temperature reporting for the E521--there are unpopulated spots on the board clearly labeled as places for thermal sensors.) This is true of other Dell systems, such as the Dim8400, 8300, 2400 and OptiPlex 170. (Systems like the Dimension 2100 and its siblings (L5xx series) have temperature/fan monitoring functions in their LPCIO ICs, but it isn't used or connected.) I could not trace the board--it has too many layers. The mechanism for actual fan speed control is obvious--a temperature sensor bulb that protrudes into the airflow from the fan will speed it up if it gets hot. I'd like to know how Dell does fan speed monitoring, and while I suspect that this may require asking a Dell system board designer how it was done, I'm hoping that someone on the group might know. William |
#3
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Dell fan speed control
William R. Walsh wrote:
I don't know if anyone knows, but I'd like to. On the "classic" Dell systems that actually had parts inside that were designed and maybe even assembled by Dell, there is clearly some type of fan monitoring that is done by the BIOS. If you pull the plug on a fan, the system will beep unhappily and tell you at POST that a fan is not responding. I've looked at a dead Dimension E521 board to see how they might do this, as looking with software such as SpeedFan shows nothing. I found that this is because the LPCIO simply doesn't have any fan speed reporting, temperature reporting or fan control functionality. (Someone thought of using at least temperature reporting for the E521--there are unpopulated spots on the board clearly labeled as places for thermal sensors.) This is true of other Dell systems, such as the Dim8400, 8300, 2400 and OptiPlex 170. (Systems like the Dimension 2100 and its siblings (L5xx series) have temperature/fan monitoring functions in their LPCIO ICs, but it isn't used or connected.) I could not trace the board--it has too many layers. The mechanism for actual fan speed control is obvious--a temperature sensor bulb that protrudes into the airflow from the fan will speed it up if it gets hot. I'd like to know how Dell does fan speed monitoring, and while I suspect that this may require asking a Dell system board designer how it was done, I'm hoping that someone on the group might know. William Take a look at the fan and you will see three wires. One is power one is ground and one is a speed signal (like a tach signal in a vehicle) The machine powers up and the fan starts to spin. The tach signal starts and the machine sees that the fan is spinning. It compares the speed to the speed it last recorded for the fan. If they are withing a certain percentage it says the fan is OK and the BIOS lets the machine continue. The thermistor on the fan also watches the air temperature across it, When the temp goes up the thermistor lets more power through and speeds up the fan. -- Steve W. Near Cooperstown, New York Life is not like a box of chocolates it's more like a jar of jalapenos- what you do today could burn your ass tomorrow! ----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= - Total Privacy via Encryption =--- |
#4
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Dell fan speed control
Hi!
Take a look at the fan and you will see three wires. I'm pretty good on understanding how the fan does its thing. :-) What I'd like to know is how Dell monitors it, since the LPCIO has no explicit support. William |
#5
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Dell fan speed control
Hi!
Your question was, is, and will be actually a 2-part question. Dell used/uses a lot of Intel-designed motherboards. I think that depends upon which Dell system you look at. Some of the boards floating around are "distinctly Dell"...I'm thinking of ones where you see the onboard Broadcom 4401 chipset for Ethernet for my example. On the other hand, I could see an Intel design being used in the Dim8300--since the Ethernet is integrated into the chipset. Intel once had very nice monitoring software that ren only on 800-series chipsets and systems with an original generic Intel BIOS (not an OEM BIOS like Dell's or Gateway's). No longer does Intel provide monitoring software, and they apparently use for controlling fan RPMs a low-level scheme something that Speedfan et al cannot detect. I've seen this monitoring software (or so I think), and have it on an Intel board with 8 PCI slots. However, that board definitely has an LPCIO that is capable of monitoring temperatures, RPMs and voltages. It does show up to SpeedFan. The other Intel board that I have is a OEM-for-Gateway D845HV board that uses an Analog Devices fan controller and an SMSC LPCIO for temperature and voltage monitoring. I would be dumbfounded if Dell's "engineering" contribution to the design and manufacture of motherboards was much more than I have described above. I dare say that the manufacturing happens elsewhere, but until recently, I also had a feeling based on looking at the boards that Dell had at least some engineers on hand or made significant input into the designs. There was a common element to most of their motherboard designs that I hadn't seen anywhere else. The modern consumer level Dell systems definitely do have fairly generic boards in them. I found a Foxconn board in an Inspiron desktop, and it does respond to fan/temperature/voltage monitoring software. William |
#6
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Dell fan speed control
The tipoff here in recent (i.e. Pentium 4) years has been the presence of an
sticker with an Intel AA "number" on it. Six digits, a hyphen, and 3 more digits. Except that the high order digit has gone to a hex digit. No matter what, Dell licenses for motherboard BIOSes give Dell the option to impose its own distinct look-and-feel on its BIOSes. I view this as a somewhat forumulaic cookie cutter operation for the BIOS programmers. No software design expertise needed. With some of the recent motherboards, Intel models now use Realtak 10/100/1000 chips, giving us a signal that Intel will soon exit from the Ethernet chip business, if it has not done so already... Ben Myers On Sun, 05 Oct 2008 05:29:49 GMT, "William R. Walsh" m wrote: Hi! Your question was, is, and will be actually a 2-part question. Dell used/uses a lot of Intel-designed motherboards. I think that depends upon which Dell system you look at. Some of the boards floating around are "distinctly Dell"...I'm thinking of ones where you see the onboard Broadcom 4401 chipset for Ethernet for my example. On the other hand, I could see an Intel design being used in the Dim8300--since the Ethernet is integrated into the chipset. SNIP |
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