An electronic device comprising: a circuit board that includes a first active component ; a number of guide walls (10A-E), wherein, when the electronic device is installed in a chassis that includes a number of fans and when the fans operate, air flows along an airflow path that flows from an air inlet channel defined by the guide walls (10A-E) to an exhaust of the chassis , the first active component being located in the airflow path downstream of the air inlet channel and upstream of the exhaust ; a thermoelectric cooler, TEC, , wherein a heat absorbing portion of the TEC extends into the airflow path upstream of the first component and a heat releasing portion of the TEC extends into the airflow path downstream of the first component , wherein the electronic device, when installed in the chassis , is connected to a rear side of a midplane of the chassis and wherein, when the fans operate, air flowing along the airflow path : flows rearward from a front side of the midplane through the air inlet channel , then flows forward on a first side of the circuit board from an opening in the air inlet channel toward the midplane , where the first active component is disposed on the first side of the circuit board , then flows upward or downward through a gap between the midplane and the circuit board , and then flows rearward on a second side of the circuit board toward the exhaust of the chassis . a circuit board that includes a first active component ; a number of guide walls (10A-E), wherein, when the electronic device is installed in a chassis that includes a number of fans and when the fans operate, air flows along an airflow path that flows from an air inlet channel defined by the guide walls (10A-E) to an exhaust of the chassis , the first active component being located in the airflow path downstream of the air inlet channel and upstream of the exhaust ; a thermoelectric cooler, TEC, , wherein a heat absorbing portion of the TEC extends into the airflow path upstream of the first component and a heat releasing portion of the TEC extends into the airflow path downstream of the first component , wherein the electronic device, when installed in the chassis , is connected to a rear side of a midplane of the chassis and wherein, when the fans operate, air flowing along the airflow path : flows rearward from a front side of the midplane through the air inlet channel , then flows forward on a first side of the circuit board from an opening in the air inlet channel toward the midplane , where the first active component is disposed on the first side of the circuit board , then flows upward or downward through a gap between the midplane and the circuit board , and then flows rearward on a second side of the circuit board toward the exhaust of the chassis . flows rearward from a front side of the midplane through the air inlet channel , then flows forward on a first side of the circuit board from an opening in the air inlet channel toward the midplane , where the first active component is disposed on the first side of the circuit board , then flows upward or downward through a gap between the midplane and the circuit board , and then flows rearward on a second side of the circuit board toward the exhaust of the chassis . <EOS>