惠普dc7900主机 q45主板能上q9550cpu吗

您好，感谢您选择惠普产品。
惠普官方在您机器上测试过的CPU型号如下，没有测试过您所述的这款CPU：
Intel Celeron 440 processor 2.0 GHz, 512 KB L2 cache, 800 MHz FSB
Intel Celeron 450 processor 2.2 GHz, 512 KB L2 cache, 800 MHz FSB
Intel Celeron dual-core E1200 processor 1.6 GHz, 512 KB L2 cache, 800 MHz FSB
Intel Celeron dual-core E1400 processor 2.0 GHz, 512 KB L2 cache, 800 MHz FSB
Intel Celeron dual-core E1500 processor 2.2 GHz, 512 KB L2 cache, 800 MHz FSB
Intel Celeron E1600 processor 2.4-GHz, 512K L2 cache, 800-MHz FSB
Intel Pentium dual-core E2200 processor 2.2 GHz, 1 MB L2 cache, 800 MHz FSB
Intel Pentium dual-core E2220 processor 2.4 GHz, 1 MB L2 cache, 800 MHz FSB
Intel Pentium dual-core E5200 processor 2.5 GHz, 2 MB L2 cache, 800 MHz FSB
Intel Pentium dual-core E5300 processor 2.6 GHz, 2 MB L2 cache, 800 MHz FSB
Intel Pentium dual-core E5400 processor 2.70 GHz, 2 MB L2 cache, 800 MHz FSB
Intel Pentium E6300 Processor 2.80-GHz, 2MB L2 cache, 800-MHz FSB
Intel Core 2 Duo E7200 processor 2.53 GHz, 3 MB L2 cache, 1066 MHz FSB
Intel Core 2 Duo E7300 processor 2.66 GHz, 3 MB L2 cache, 1066 MHz FSB
Intel Core 2 Duo E7400 processor 2.80 GHz, 3 MB L2 cache, 1066 MHz FSB
Intel Core 2 Duo E7500 Processor 2.93 GHz, 3 MB L2 cache, 1066 MHz FSB
希望以上回复能够对您有所帮助。

945的主板是LGA 775针脚的，q9550 CPU也是LGA 775针脚的，理论上是支持的