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30-673: The Phenom II X4 operates as the processor component of AMD's Dragon Platform , which also includes the 790 series chipset and Radeon HD 4800 series graphics. The Thuban Phenom II X6 is the CPU in the Leo Platform which also includes the AMD 890 chipset and the Radeon HD 5800 series graphics. The Phenom II triples the shared L3 cache size from 2MB (in the original Phenom line) to 6MB, leading to benchmark performance gains as high as 30%. In another change from

60-403: A statistical sample of a population (or non-human factors) in which all participants are not equally balanced or objectively represented. It is mostly classified as a subtype of selection bias, sometimes specifically termed sample selection bias , but some classify it as a separate type of bias. A distinction of sampling bias (albeit not a universally accepted one) is that it undermines

90-400: A Phenom II X4 940 and a DFI LANParty 790FXB-M2RS with a combination of liquid nitrogen and liquid helium cooling to take the processor to a clock rate of 6.5 GHz and succeeded in beating the world record 3DMark 2005 score with a total of 45474. A group named LimitTeam successfully overclocked AMD’s Deneb 45 nm Phenom II X4 955 processor (Black Edition) on April 30, 2009, and submitted

120-473: A desire for approval, personal relation to the study topic and other reasons. As with most instances mitigation in the case of volunteer bias is an increased sample size. In the general case, selection biases cannot be overcome with statistical analysis of existing data alone, though Heckman correction may be used in special cases. An assessment of the degree of selection bias can be made by examining correlations between exogenous (background) variables and

150-530: A lengthy time period. Non-Response or Retention bias can be influenced by a number of both tangible and intangible factors, such as; wealth, education, altruism, initial understanding of the study and its requirements. Researchers may also be incapable of conducting follow-up contact resulting from inadequate identifying information and contact details collected during the initial recruitment and research phase. Philosopher Nick Bostrom has argued that data are filtered not only by study design and measurement, but by

180-407: A special power-supply feature, often called "dual power-plane". It's supported by default in all native AM3 mainboards, however not in most AM2+ mainboards, even those advertised as "AM3 optimized" or "AM3 ready". Processor running below its nominal speed (i.e. at 800 MHz), clock and multiplier locked are symptoms of this incompatibility. This is caused by the processor itself: when it detects that

210-438: A test of a dieting program, the researcher may simply reject everyone who drops out of the trial, but most of those who drop out are those for whom it was not working. Different loss of subjects in intervention and comparison group may change the characteristics of these groups and outcomes irrespective of the studied intervention . Lost to follow-up , is another form of Attrition bias, mainly occurring in medicinal studies over

240-418: A treatment indicator. However, in regression models, it is correlation between unobserved determinants of the outcome and unobserved determinants of selection into the sample which bias estimates, and this correlation between unobservables cannot be directly assessed by the observed determinants of treatment. When data are selected for fitting or forecast purposes, a coalitional game can be set up so that

270-457: Is a stub . You can help Misplaced Pages by expanding it . Selection bias Selection bias is the bias introduced by the selection of individuals, groups, or data for analysis in such a way that proper randomization is not achieved, thereby failing to ensure that the sample obtained is representative of the population intended to be analyzed. It is sometimes referred to as the selection effect . The phrase "selection bias" most often refers to

300-409: Is closely related to the survivorship bias , where only the subjects that "survived" a process are included in the analysis or the failure bias , where only the subjects that "failed" a process are included. It includes dropout , nonresponse (lower response rate ), withdrawal and protocol deviators . It gives biased results where it is unequal in regard to exposure and/or outcome. For example, in

330-501: Is due to the BIOS, not the memory controller; several board manufacturers have addressed the issue with a BIOS update. The dual-spec memory controller also gives motherboard manufacturers and system builders the option of pairing AM3 with DDR2, as compared to competing chips from Intel which require DDR3. "Thuban" and "Zosma" Phenom II processors support AMD's Turbo Core overclocking performance-boost technology. When not all cores are needed,

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360-532: Is impossible to know whether an unlocked core is truly bug-free. According to AMD , Black Edition CPUs are "designed to help you unleash the maximum potential of your system with tunable performance." What this means is that the core multiplier is unlocked, allowing for modification of the CPU speed without changing the FSB or HyperTransport. On a non-black edition CPU, the multiplier is allowed to only be lowered. The standard processors allow for overclocking, however not to

390-520: Is to offer the user a powerful gaming system. Having a level 3 cache memory of 6 megabytes and support for the latest DDR3 memories, AMD claims the Dragon platform will allow for up to 20 percent faster performance than previous platforms. The first versions are available for mainboards offering an AM2+ socket, supporting DDR2 memories, but the AM3 socket using DDR3 memory will be the primary socket type for

420-628: The external validity of a test (the ability of its results to be generalized to the rest of the population), while selection bias mainly addresses internal validity for differences or similarities found in the sample at hand. In this sense, errors occurring in the process of gathering the sample or cohort cause sampling bias, while errors in any process thereafter cause selection bias. Examples of sampling bias include self-selection , pre-screening of trial participants, discounting trial subjects/tests that did not run to completion and migration bias by excluding subjects who have recently moved into or out of

450-472: The Dragon platform. A system conforming to the platform specification was said to be a combination of a Phenom II X4 processor and a mainboard using a chipset from the AMD 700 chipset series , along with a graphics card of the ATI Radeon HD 4800 series. Pre-built systems using the platform were offered by Dell , HP and Alienware among others. This microcomputer - or microprocessor -related article

480-607: The Phenom II's pin compatibility, the AM3 memory controller supports both DDR2 and DDR3 memory (up to DDR2-1066 and DDR3-1333), allowing existing AM2+ users to upgrade their CPU without changing the motherboard or memory. However, similar to the way the original Phenom handled DDR2-1066, current Phenom II platforms limit the usage of DDR3-1333 to one DIMM per channel; otherwise, the DIMMs are under clocked to DDR3-1066. AMD claims that this behaviour

510-457: The average consumer could expect using traditional air cooling even with expensive third party cooling fans. For instance, maximum overclocking on a Phenom II X4 955 processor using a heatsink and fan is approximately 4 GHz. AMD Dragon AMD Dragon is a platform engineered for gamers , designed for use with the AMD Phenom II X4 processor family. The goal for the platform

540-500: The chips themselves marked as a lower-grade product. Some versions of the Phenom II X2 and X3 have one or two cores "deactivated" to enable AMD to target the lower end of its market. However, from outside, a user can never determine whether the disabling of the core(s) was merely due to marketing reasons (with the disabled cores being fully functional in reality) or whether they are actually defective hardware-wise. So even though with

570-446: The correct motherboard and BIOS, it is possible to unlock the deactivated core(s) of the processor, success is never guaranteed, because the user might catch the awkward case where one or more core(s) were deactivated due to faulty silicon. Hardware enthusiast websites have collected and summarized anecdotal reports that, overall, indicate about a 70% success rate, but these reports likely have self-reporting bias , and more importantly, it

600-403: The distortion of a statistical analysis , resulting from the method of collecting samples. If the selection bias is not taken into account, then some conclusions of the study may be false. Sampling bias is systematic error due to a non- random sample of a population, causing some members of the population to be less likely to be included than others, resulting in a biased sample , defined as

630-683: The motherboard does not supply dual power planes, the chip locks its multiplier to 4x. This issue is not resolvable via a BIOS update; however, users of AM2 and AM2+ motherboards can still use Phenom II processors excluding the 125 Watt variants. Beginning with the AM3 versions, Phenom II CPUs are based on two dies: the original Deneb die with four cores and the new Thuban die with six. These are divided into five series for marketing. The first two series are flagships based on full dies. The other three series are formed from Deneb dies by die harvesting, that is, chips that were produced with some amount of defects. The affected portions of these chips are disabled and

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660-418: The nature of this feature, it reduces the effectiveness of overclocking the CPU and RAM, but also decreases power consumption and heat output. Socket AM2+ versions of the Phenom II (920, 940) lack forward-compatibility with Socket AM3. Socket AM3 versions of the Phenom II are backwards-compatible with Socket AM2+ , though this is contingent on motherboard manufacturers supplying BIOS updates. In addition to

690-484: The necessary precondition that there has to be someone doing a study. In situations where the existence of the observer or the study is correlated with the data, observation selection effects occur, and anthropic reasoning is required. An example is the past impact event record of Earth: if large impacts cause mass extinctions and ecological disruptions precluding the evolution of intelligent observers for long periods, no one will observe any evidence of large impacts in

720-409: The original Phenom, Cool'n'Quiet applies to the processor as a whole, rather than on a per-core basis. AMD implemented this to address the mishandling of threads by Windows Vista , which can cause single-threaded applications to run on a core that idles at half its clock rate. This feature can be disabled through BIOS options on most motherboards, which allows for customization and overclocking. Due to

750-535: The point that a Black edition CPU will. The Phenom II range of CPUs is the first series of AMD CPUs to have a low enough minimum temperature of operation to support "extreme" cooling methods such as dry ice , liquid nitrogen or liquid helium , a deficiency in older CPUs referred to as the "Cold Bug". In a public demonstration of the Phenom II's overclocking potential at CES 2009 in Las Vegas on 10 January 2009, Sami "Macci" Mäkinen (a record-breaking overclocker) used

780-400: The processor will automatically overclock up to half of the cores by up to 500 MHz, leaving the other half idle. In turn, when the application demands more than half of the cores, the processor will run on standard clock rate and with all cores enabled. The flagship AMD Phenom II X6 1100T shifts 3.3 GHz to 3.7 GHz. Some top-level AM3 processors (x945 125W, x955 and x965) require

810-469: The recent past (since they would have prevented intelligent observers from evolving). Hence there is a potential bias in the impact record of Earth. Astronomical existential risks might similarly be underestimated due to selection bias, and an anthropic correction has to be introduced. Self-selection bias or a volunteer bias in studies offer further threats to the validity of a study as these participants may have intrinsically different characteristics from

840-575: The results for validation to CPU-Z. During the process, the group used the Asus M4A79T Deluxe motherboard, dubbed as the Asus “multidimensional performance platform” featuring support for an AMD 140W CPU and the AMD 790FX/SB750 chipset. As a result, the group reached 7.127 GHz, beating the previous score of 6.7 GHz. Note that these extreme overclocks involve specialized equipment and are nowhere near what

870-420: The study area, length-time bias , where slowly developing disease with better prognosis is detected, and lead time bias , where disease is diagnosed earlier for participants than in comparison populations, although the average course of disease is the same. Attrition bias is a kind of selection bias caused by attrition (loss of participants), discounting trial subjects/tests that did not run to completion. It

900-433: The target population of the study. Studies have shown that volunteers tend to come from a higher social standing than from a lower socio-economic background. Furthermore, another study shows that women are more probable to volunteer for studies than males. Volunteer bias is evident throughout the study life-cycle, from recruitment to follow-ups. More generally speaking volunteer response can be put down to individual altruism,

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