Need some advice about CPU

You could upgrade to a core processor which I found while looking on the manual, I don't know which one.

Does not support 45nm processors

Intel Core 2 Duo, Intel Pentium D, Pentium 4 HT, Celeron D, Celeron 4xx - bios update may be required

source for info.

en.wikipedia.org/.../Dell_OptiPlex

The 745 supports the following OEM (original equipment manufacturer) Core 2 Duo -
E6300 1.86GHz
E6400 2.13GHz
E6600 2.40GHz
E6700 2.66GHz

I heard that the Intel® Core™2 Quad Processor Q6700 is also supported since its 65nm but im not sure, so theres no officaly supported quad cores for the optiplex 745?

Thx for the replys.

The Optiplex 745 has an Intel Q965 chipset, which does NOT support the Q6700 processor (or any quad-core for that matter), so the Q6700 is a NO GO in the 745.  The best processor you can upgrade to is the E6700 (dual-core).

ark.intel.com/.../22756

ark.intel.com/.../Intel-Pentium-Processor-E6700-(2M-Cache-3_20-GHz-1066-FSB)

From personal experience I know that the Optiplex 745 will support the Q6600 2.4GHz and the Q6700 2.66GHz.  However, if you're current heatsink is the silver colored all-alluminum version then you will need to upgrade it to the version which has copper bottom and heatpipes sticking out the top.

Hmm thx for the info,so what you guys recommend to get a Core 2 Duo with 2,4Ghz or a Dual Core proccesor with 3Ghz.

I know that the Core 2 Duo is the second generation and works faster then the dual cores but i dont know how big the speed difference is.

If this helps:

Pentium Dual-Core E5700 @ 3.00GHz:
www.cpubenchmark.net/cpu_lookup.php

Intel Core2 Duo E6600 @ 2.40GHz:
www.cpubenchmark.net/cpu_lookup.php

jms ... I still have my doubts about the Q6600/Q6700 in the 745 ... unless there is some revision of it with a different chipset or the system was other wise modded from the original parts, I don't see how it could possibly work without chipset support.

Bios must be updated BEFORE changing CPU.

Intel® Core™2 Duo Processor E6700 (4M Cache, 2.66 GHz, 1066 MHz FSB)
Intel® Core™2 Duo Processor E6600 (4M Cache, 2.40 GHz, 1066 MHz FSB)
Intel® Core™2 Duo Processor E6420 (4M Cache, 2.13 GHz, 1066 MHz FSB)
Intel® Core™2 Duo Processor E6400 (2M Cache, 2.13 GHz, 1066 MHz FSB)
Intel® Core™2 Duo Processor E6320 (4M Cache, 1.86 GHz, 1066 MHz FSB)
Intel® Core™2 Duo Processor E6300 (2M Cache, 1.86 GHz, 1066 MHz FSB)

I updated my bios to the latest version 2.6.4 i think. I still dont know wich cpu i gonna get the Core 2 Duo E6600 with 2,40 Ghz or a Dual Core with 3Ghz wich one runs faster? The old duals cores with 3Ghz or the second generation C2D with 2,4Ghz?

Pentium D 925 (Dual Core 3.0GHz - 1066MHz FSB, 4MB cache):
cpubenchmark.net/cpu_lookup.php

Pentium Core 2 Duo E6600 (Core 2 Duo 2.4GHz - 800MHz FSB, 4MB cache):
www.cpubenchmark.net/cpu_lookup.php

Side-by-Side Comparison of Specifications:
ark.intel.com/.../27517,27250

Other than looking at available benchmarks and specifications, you'd have to find someone that has tried/tested both to get better insight, but the newer processors will out perform the older processors pretty handily.

(I previously linked to an E5700 ... not sure why ... I may have gotten confused with another thread.)