Patent Application
20120151242
The present invention generally relates to computers. More particularly, this invention relates to methods and systems for monitoring power consumption of computer components, such as a central processing unit (CPU) of a desktop computer.
Central processing units (CPUs) have evolved over the last decades from relatively simple RISC or x86 processors with a single execution unit to hyperscalar processing units featuring several instances of separate arithmetic logic units and floating point units, decoders and schedulers. In addition, almost all current midrange to high-end processors feature several layers of integrated cache memory comprised mostly of on-die SRAMs. Recent developments have further placed the memory controller onto the processor die. The microprocessor industry has also seen the emergence of multicore processors, that is, the combination of several complete processors into a single package for advanced parallel processing of multiple threads.
It is understood that such evolution of microprocessors incurs costs with regard to the number of transistors per processor. The Intel® “Kentsfield” quad core features no less than 582 million transistors. Moreover, clock speeds of microprocessors have increased about 50× over the past decade. Increased transistor count along with increased clock speed translates into increased thermal dissipation as well. Therefore, a substantial amount of effort and research has gone into power and thermal management of CPUs. Some measures have involved software-based throttling on the level of the operation system, and others are embedded within the Basic Input/Output System (BIOS).
A prerequisite for successful power management is the understanding of where and under what circumstances most of the power is being consumed. This understanding, however, cannot be achieved without acquisition and analysis of power consumption-related data. On the system level, this can be done through power meters interposed between the wall outlet and the computer's power supply unit. However, this method does not take into account the different loads on the individual system components and can only generate a summary report. On the other hand, for targeted, specific monitoring of the power consumption of, for example, the CPU, this method is not suitable because all other system components, including the power supply's efficacy, mask the real power consumption of the CPU itself.
Currently, power monitoring is predominantly done on the system level through devices like Seasonic's Power Angel or Extech 380308 Power Analyzer. In mobile applications (e.g., notebooks, laptops, PDAs, etc.), power consumption is sometimes monitored using specific software to interface with current sensors. On the desktop level, so far, no easy way exists to monitor specifically the isolated power consumption of the CPU as a function of load.
In view of the above, it would be desirable if it were possible to monitor specifically the isolated power consumption of a desktop CPU (or like motherboard device) as a function of load. Exactly this kind of monitoring is pivotal for an optimal configuration of the computer hardware as well as the optimal load balancing between several computers for the purpose of the most energy-efficient operation of all computer systems. This is true especially in server and workstation environments. In addition, even for a single user, monitoring of the CPU power consumption may give some valuable information about background processes that are using an excess of power.
The present invention provides a system and method suitable for monitoring power consumption of a central processing unit (CPU) or other power-consuming component of a desktop computer system.
According to a first aspect of the invention, a computer system component mounted on a substrate is supplied with supply power from a power supply unit of the computer through a power supply cable, and the system includes a coupling that is disposed between the power supply unit and the substrate and is electrically connected to at least one power supply line of the power supply cable and a power supply connector on the substrate. The at least one power supply line carries a supply voltage, and one or more devices associated with the coupling determine current flow through the at least one power supply line and provides a power consumption reading for the component based on the supply voltage and the current flow through the at least one power supply line.
According to a second aspect of the invention, the method entails supplying a computer system component mounted on a substrate with supply power from a power supply unit of the computer through a power supply cable, and placing a coupling between the power supply unit and the substrate so that the coupling is electrically connected to at least one power supply line of the power supply cable and a power supply connector on the substrate. With the at least one power supply line carrying a supply voltage, current flow through the at least one power supply line is determined, and a power consumption reading for the component is generated based on the supply voltage and the current flow through the at least one power supply line. In the case of a modular power supply unit with removably attached cables, the coupling can also be an integral part of the cable and use the temperature-dependent resistance of a wire within the cable as a resistor.
According to certain preferred aspects of the invention, multiple power supply lines are consolidated within the coupling into a single conductor, through which current flow is determined. A resistor can be combined with the conductor, across which a voltage differential is measured to determine current flow through the power supply lines. Alternatively, the coupling may include a Hall effect transducer adapted to sense current flow through the power supply line(s).
According to other aspects of the invention, the power supply unit modulates its output voltages to match conditions corresponding to energy efficient voltage conversion at the component as determined as current flow through the coupling. A voltage drop across the coupling can further indicate an over-current condition and trigger shut-down of the power supply unit. In modular power supply units with removable cable harness, independent modulation of the output voltages for more than one DC outlet can be used to accurately match the dynamic requirements of multiple components.
In view of the above, it can be seen that a significant advantage of this invention is that it provides a system and method for monitoring the isolated power consumption of a CPU, as well as other computer system components. The system and method enable one to optimize the hardware configuration of a computer, as well as optimize load balancing between several computers for the purpose of energy-efficient operation of several computer systems in, for example, a server or workstation environment. Moreover, the invention allows for modulating the output voltage of the power supply unit to better match the harmonics of the supply voltage to system components and thereby provide a basis for a more energy-efficient conversion.
Other aspects and advantages of this invention will be better appreciated from the following detailed description.
The present invention takes advantage of the fact that increased power consumption of recent CPUs has resulted in CPUs being provided with power through power supply lines that are separate from the remainder of the computer system power. Generally, before the emergence of the Intel® Pentium® 4, CPU power was usually derived from either the 3.3V or the 5V rail supplied through AT or ATX power connectors. The increased power demand of the Pentium® 4 led to the use of dedicated supply lines at higher voltages, typically dedicated 12V auxiliary power supply lines, to power the CPU. Currently most CPU and motherboard designs use processor power circuitry electrically isolated from the rest of the motherboard's power and ground planes.
According to the present invention, the separation of the CPU supply power from other power and ground planes on the motherboard permits the use of the present invention, which entails monitoring the CPU's power consumption by measuring current flow through dedicated power supply lines (typically 12V) to the CPU. It should be noted that CPUs typically receive a constant voltage supply level appropriate for the particular CPU from a voltage regulator module (VRM) on the motherboard. Though the efficacy of a given VRM is not precisely defined, VRM efficacy is generally believed to be on the order of about 70 to 80%, which is sufficiently precise for purposes of implementing the present invention.
With knowledge of the supply voltage delivered by the supply lines 18 to the CPU, the invention monitors current flow through the supply lines 18 in order to compute CPU power consumption. A first and readily uncomplicated approach is schematically represented in
The resistor 26 is preferably a relatively low Ohm resistor, for example, about 0.01 to 0.05 Ohm, so as to minimize the voltage drop in the supply power to the CPU. Based on Ohm's law, V=IR, it can be understood that a 5 Amp current flowing through the power supply lines 18 would result in a measurable 0.05V drop across the resistor 26, which is easily tolerated by the CPU VRM yet can still be accurately be sensed. The 50 mV differential can be measured across two test points 28 and 30 located at or adjacent opposite ends of the resistor 26 and sensed by a voltmeter 34 (such as an analog-digital (AD) converter) or other suitable voltage sensor associated with the coupling 12. With knowledge of the supply voltage on the power supply lines 18, the differential across the test points 28 and 30 can be monitored and used to reliably calculate the total power going to the CPU based on the equation, P=IV, in which I is the calculated current through the resistor 26, V is the supply voltage, and P is the power consumption in Watts. As noted above, the CPU power consumption can be more accurately calculated by further factoring in the efficacy of the VRM. The voltmeter 34 or other suitable processing unit can be adapted to convert and display the power consumption of the CPU. For example, the voltmeter 34 can be connected to a digital display 46 configured to be installed in a drive bay, or implemented in any other manner suitable for a desktop computer. Alternatively, the display 46 could incorporate circuitry to also perform the measuring and conversion functions of the voltmeter 34.
In the second embodiment of
In a third embodiment, the power supply lines 18 are in the form of one or more modular cables, that is, cables that are plugged into a DC outlet at the PSU 2s. Moreover, the cables themselves are calibrated and have a known resistance, including a temperature coefficient that can be used to calculate the current passing through, based on the case temperature and the voltage drop. In other words, the temperature-dependent internal resistances of the cables are used instead of a dedicated interposed resistor.
In order to counteract voltage drops on the supply lines 18 that may occur at high loads,
Most load compensation devices known in the art work through a feedback loop, that is, the output voltage is monitored through a feedback pin by the power supply. Typical solutions employ a TL431 programmable shunt regulator in conjunction with an optoelectric coupler or optocoupler to provide feedback loop isolation. This allows for accurate control of either the voltage or the ripple supplied to the targeted device (for example, a CPU) or the connector connecting to the targeted device. In this context, it is further interesting to note that especially in the case of multi-phase voltage regulators, slight variations in the input power can have substantial impact on the energy-efficiency of the entire system. Especially when down-regulation of voltage (from relatively high voltage to a lower voltage) is involved, better efficiency is achieved if the target voltage is a harmonic of the source voltage. For example, going from 12V to 1V on a 12-phase voltage regulator module is more efficient than going to, for example 0.98V or 1.05V. However, efficiency can be boosted if the input voltage would trail the output voltage, in this case it would drop to 11.76V or increase to 12.6V. The net effect in this case is less current draw and less heat generation, meaning that the system runs more energy efficient and cooler. A side effect in this case is the reduction of ripple current, meaning that the output power is cleaner.
The aspects described above are of particular importance given the dynamic adjustment of supply voltages of modern computer components based on load. For example, under idle conditions, typical Intel® or AMD® processors move to the lowest performance state (P-state), which means they will go to the lowest supported frequency and the lowest supported supply voltage at around 0.95V. As soon as there is load on the processor, it will go to a higher P-state, meaning that the processor signals to the voltage regulator module (VRM) that it needs higher supply voltage before ramping up its core frequency. Typical load supply voltages are around 1.3 to 1.4V. In light of the above, modulation of the output voltage of the power supply, that is, the voltage going into the VRM, may have a pronounced effect on the efficiency of the VRM itself and also reduce noise in the supply voltage to the processor.
Without knowing the actual output voltages, especially in a computer system with several independently acting components, it is nearly impossible to predict the most efficient input voltage for the highest system power efficiency based on known target voltages. Moreover, it is not even necessary to know the target voltage since a power supply with enough intelligence to adjust the input voltage while monitoring the actual power consumption will be able to identify the highest system power efficiency based on the lowest power draw regardless of the behavior of the individual components. Accordingly, the load compensation device could use a microprocessor functionally connected to the TL431 shunt connector to perform output voltage modulation—within the tolerances of the specifications of the device (such as, for example the ATX specifications of ±5%)—and lock the voltage when, depending on the desired mode of operation, the minimum power consumption or the smallest ripple is measured.
Such scans can be performed either periodically or every time a change in load occurs. Current PSUs sample feedback voltage at about 1000 Hz, meaning that a complete scan can be done with reasonable accuracy in about 50 msec. In order to avoid over-nervous transients, hysteresis or inertia is designed in.
In most cases the system will spend most of the time close to idle which is typically the range of the lowest efficiency. Among other reasons, this is a consequence of most efforts being spent on optimizing efficiency at high load. The minimum and maximum power efficiency could then also be displayed, or else, the energy savings at any load compared to either a static input voltage or an average based on the scanned range of input voltages.
As energy efficiency of electronics is becoming increasingly more important, it is foreseeable that microprocessors will be used in future designs to accurately control the voltages generated by a PSU not only on a per voltage rail basis, but rather for each supply cable to match the specific load characteristics and requirements of a targeted device (for example, a CPU). Accordingly, a power supply could have a “core” voltage that is then adjusted at the output node to the system for each cable.
According to Ohm's law, power (in Watts) is the product of current and voltage. This allows for the monitoring of over-current or-over power situations, in that the voltage will drop if the current increases beyond a specified or tolerated maximum. If the voltage drops below a certain level, then this can be used to trigger shut-down of the PSU in order to protect the system. In contrast to the current state of the art, this aspect of the invention allows for the implementation of overcurrent protection on a per-device level, since it is the direct supply to the device that is monitored via the cable. These and other additional aspects of the invention are represented in
From the above, the present invention can be seen to provide several advantages, most notably, the ability to accurately isolate and monitor CPU power consumption with hardware that is both inexpensive and uncomplicated to implement. Moreover, by monitoring the power consumption as a function of voltage modulation on different rails, it is possible to adjust the voltages generated by a PSU to optimally match the most efficient input voltage range for the processor VRM under any load conditions. In addition, an extra level of device protection is implemented by avoiding over-current situation on the level of the supply cable. It should be noted that essentially the same equipment and method described above can be used to monitor the power consumption of other computer system components with dedicated supply power, including but not limited to graphics processors (GPUs) and graphics cards featuring on-board memory and a graphics processor. Particularly in the case of graphics adapters with power requirements of up to 400 W in the latest implementations power optimization and over-current protection is of paramount importance. As such, the invention is not limited to monitoring the power consumption of a CPU on a motherboard, but can be applied to a variety of other components that may be mounted to any suitable circuit board or substrate equipped with appropriate connections to a power supply of a computer.
In view of the above, while the invention has been described in terms of specific embodiments, it is apparent that other forms could be adopted by one skilled in the art. Furthermore, the functions of certain components could be performed by components of different construction but capable of a similar (though not necessarily equivalent) function. Therefore, the scope of the invention is to be limited only by the following claims.
This application is a continuation-in-part patent application of U.S. patent application Ser. No. 11/938,343, filed Nov. 12, 2007, which claims the benefit of U.S. Provisional Application No. 60/865,182, filed Nov. 10, 2006. The contents of these prior patent documents are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60865182 | Nov 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11938343 | Nov 2007 | US |
| Child | 13159557 | US |
