由於高科技電子產品推陳出新，電腦運算速度越來越快，功率也越來越高，相對地帶來越來越大的熱源，其所產生的高溫也是電子元件損壞的主因。面臨此問題，模組廠商已成功開發出散熱能力可達160W或更高的散熱模組，但卻需添加額外的設備及成本。本研究著手思考不改變散熱模組之條件下，研究改變CPU於伺服器機殼內部的位置，尋找出CPU於機殼內的最佳散熱位置，觀察其散熱差異。
本文共分為三個主題來討論：（1）密閉系統中，不同CPU發熱功率搭配放置不同位置，對散熱效益的影響力比較；（2）不同CPU位置與發熱功率下，搭配機殼上不同風扇數量與位置，散熱效益的比較；（3）相同CPU位置與功率下，搭配機殼內不同通道，風扇數量、位置、大小與進出風方向，散熱效益的比較。
實驗結果發現系統熱阻會隨著晶片消耗功率的增加而呈線性下降；最佳的CPU散熱位置是位於機殼內部較低之位置，因為熱空氣密度輕會流動至空間的上方，再藉由機殼上方的風扇，利用強制對流將熱空氣導引至外部環境；且增設空氣通道專屬於散熱模組，空氣流動方向呈直線運動時風阻較低，可以更有效帶走經由散熱模組傳導出來的CPU熱量。

Because high-tech electric products bring forth the new through the old, they cause the higher and higher power as their computing speeds become faster and faster. The resulting high temperature is the major damage cause for electronic components. To face this problem, module factories has successfully developed a kind of module that could dissipate up to 160 W. However, it needs extra equipment and cost. In this study, the positions of CPU in a computer sever are changed, their effects on the heat dissipation are investigated and the optimal heat-dissipation cases are found.
In this thesis, three primary subjects are studied: (1) the performance comparison of the heat dissipation for different CPU powers and positions in a closed system, (2) the performance comparison of the heat dissipation for different CPU powers and positions with different number and locations of electric fan, (3) the performance comparison of the heat dissipation for fixed CPU power and position with different air tunnels and different fan sizes, number and positions.
From the experimental results, it can be found that the thermal resistance of the whole system decreases linearly with the increase of the CPU power. The best CPU position for heat dissipation is located at the bottom portion of a computer case, from which the heated air rises up to the upper portion of the case and goes out to the external environment due to the force convection caused by the electrical fan installed in the upper part of the case. In the installation of the air tunnel for the thermal module, if the air tunnel goes straight, the air in the tunnel has the smaller flow resistance and then takes away the heat from the CPU through the module more efficiently.

[1]Bert Topelt, Daniel Schuhmann, Frank Volkel and The Editors of Tom's Hardware, “Tom's Summer CPU Charts Assault ,” Tom's Hardware US, http://www.tomshardware.com/reviews/cpu-charts-summer-2006,1304-2.html.
[2]Bert Topelt, Daniel Schuhmann, Frank Volkel and Patrick Schmid, “Tom‘s Hardware的2007 CPU比較表,” Tom's Hardware China, http://www.tomshardware.com/cn/1302,review-1302-10.html.
[3]R. Prasher, J. Y. Chang, I. Sauciuc, S. Narasimhan, D. Chau,G. Chrysler, A. Myers, S. Prstic and C. Hu, “Nano and Micro Technology-Based Next-Generation Package-Level Cooling Solutions,” Technology and Research, Intel Technology Journal, Electronic Package Technology Development, http://www.intel.com/technology/itj/2005/volume09issue04/art03_nanoandmicro/p02_intro.htm.
[4]R.R. Tummala, ”Fundamental of Microsystems Packaging, ”
McGraw-Hill Book Company, New York, 2001.
[5]Rao R. Tummala, 陳信文, 陳立軒, 林永森與陳志銘, “微系統構裝基礎原理,” 高立圖書, pp.221, 2002/12初版.
[6]C. Belady, “Cooling and Power Considerations for Semiconductors into the Next Century,” ISLPED’01, August 6-7, Huntington Beach, California, USA, 2001.
[7]張佑維, “桌上型電腦散熱流場之數值模擬分析,” 國立中興大學機械工程研究所碩士論文, 2002.
[8]吳耀國, “桌上型電腦散熱流場之最佳化分析,” 國立中興大學機械工程研究所碩士論文, 2003.
[9]王志賓, “CPU散熱片散熱效應之研究,” 國立成功大學工程科學研究所碩士論文, 1995.
[10]陳建宏, “CPU散熱片散熱效率之研究,” 國立成功大學工程科學研究所碩士論文, 1998.
[11]S. Shuler, “Thermal management：understanding how to incorporate effective thermal strategies into overall portable electronic design for better performance,” Materials and Design 21, pp.39-44, 2000.
[12]C.L. Chapman, S. Lee, and B.L. Schmidt, “Thermal performance of an elliptical pin fin heat sink,” Tenth Annual IEEE Semiconductor Thermal Measurement and Management Symposium. IEEE, pp24-31, 1994.
[13]胡文彧, “風扇流場之數值模擬與量測,” 國立交通大學碩士論文, 1998.
[14]K. Azar and C.D. Mandrone , “Effect of Pin Fin Density of the Thermal Performance of Unshrouded Pin Fin Heat Sinks,” Ninth Annual IEEE , 1995.
[15]A.T. Morrison , “Optimization of Heat Sink Fin Geometries for Heat Sinks in Natural Convection,” Inter Society Conference on Thermal Phenomena, 1992.
[16]P. Sathyamurthy and P.W. Runstadler, ” Numerical and Experimental Evalution of Planar and Staggerred Heat Sink,” Inter Society Conference on Thermal Phenomena, Vol. 5, No.7, pp.132-139, 1996.
[17]R. L. Liton, “CFD Model of Electronic Enclosures,” ASME Heat Transfer in Electronic Equipment, HTD-Vol.171, pp.95-100, 1991.
[18]R. L. Liton, and D. Agonafer, “Thermal Model of a PC,” ASME Journal of Electronic Packaging, Vol.116, pp.134-137, 1994.
[19]T. Y. Lee and M. Mahalingam, “Application of a CFD Tool for System-Level Thermal Simulation,” IEEE Transactions on Components, Packaging, and Manufacturing Technology-Part A, Vol.17, No.4, pp.564-571, 1994.
[20]林致遠, “PentiumⅡ處理器上之熱傳分析,”大同工學院機械工程研究所碩士論文, 1999.
[21]E. Thurlow, E. Prather, and V. Mansingh, “Fan Swirl Effects on Cooling Heat Sinks and Electronic Packages,” Sixteenth IEEE SEMI-THERM Symposium, Vol.1, No.7, pp.91-98, 2000.
[22]C-W. Yu and R. L. Webb, “Thermal Design of Desktop Computer System Using CFD Analysis,” Seventeenth IEEE SEMI-THERM Symposium, 2001.
[23]Christopher A. Soule, “Future Trends in Heat Sink Design,” Electronics Cooling, February, 2001.
[24]Mike Turner and Comair Rotron, “All You Need to Know About Fans,” Electronics Cooling, January, 2000.
[25]吳俊鞍, “迷你電腦系統的熱流場分析與實驗,” 國立台灣科技大學機械工程所碩士論文, 2006.
[26]鄭昱韋, “晶片用環型水冷器之研究,” 國立中山大學機械與機電工程研究所碩士論文, 2003.
[27]J. R. Rujano, R. Cardenas, M. M. Rahman and W. A. Moreno, “Development of a Thermal Management Solution for a Ruggedized Pentium Based Notebook Computer,” IEEE Inter Society Conference on Thermal Phenomena, pp.8-14, 1998.
[28]T. Nguyen, M. Mochizuki, K. Mashiko, Y. Saito, I. Sauciuc and R. Boggs, “Advanced Cooling System Using Miniature Heat Pipes in personal computers,” IEEE Inter Society Conference on Thermal Phenomena, pp.507-511, 1998.
[29]www.apple.com
[30]www.intel.com
[31]www.amd.com
[32]林憲德, “建築及空調節能設計規範的解說與實例,” 立宇出版社, pp.45,1995/04初版.
[33]F. S. Tse and I. E. Morse, “Measurement and Instrumentation in Engineering,” Marcel Dekker, Inc, 1989.