Best CPU for LGA775 for an Intel Q35 Express chipset?

Yes, Possibly the E8600 will work, but it is not in the spec sheet.
For $10 it's not much of a gamble

muchomurka said:

Personally I replaced E8400 by Q9550 (which is a bit slower but quadcore) and both the operating system and applications run much better. But i do not care...

But applications and stuff don't really care about how much cores you have, and 2 of them are more than enough to cover their demands. What I'm trying to say is that if you use a dual core that scores 1400 single thread, it's gonna be better at everything than a quad core that scores 1300 single thread, better at everything but compressing files, rendering videos, etc...

How can I know if the E8600 is supported?

The Q9650 is still a bit expensive, $30 or so, while the Q9550 is only $15. May be a should go with the Q9550.

But applications and stuff don't really care about how much cores you have, and 2 of them are more than enough to cover their demands.

1. You cannot run only one process at your comp, see Task Manager - Performance.
2. Many processes are multithreaded.
3. Quadcore has twice bigger caches.
So quadcore almost always gives performance boost (but also penalty of higher power consumption).

How can I know if the E8600 is supported?

Take CPU-Z, it should say you which mobo you have. Then find its specs. But you can be disappointed by E8600 I am afraid... It is your choice.

muchomurka said:

1. You cannot run only one process at your comp, see Task Manager - Performance.
2. Many processes are multithreaded.
3. Quadcore has twice bigger caches.
So quadcore almost always gives performance boost (but also penalty of higher power consumption).
Take CPU-Z, it should say you which mobo you have. Then find its specs. But you can be disappointed by E8600 I am afraid... It is your choice.

OK, then the Q9550 it is.

But make sure whether your power supply and mobo can support 95W & 1333MHz FSB processor.

rambomhtri said:

I READ that page 10 and I can only see a list of CPU's, not a list of the requirements of the CPU. That's why I asked where are the reqs.

Here's a comparison:
PassMark - CPU Comparison Intel Core2 Duo E6750 vs Intel Core2 Duo E8600 vs Intel Core2 Quad Q9650

As you can see, E8600 get 1370 in single thread, while the Q9650 only 1260. I think this is what makes most impact in a day to day basis, the tasks that use the 4 cores at maximum are very few and don't really do them.

I believe, correct me if I'm wrong, that the E8600 will be faster (slightly) than the Q9650 at opening programs, loading apps, loading the system and all that kind of stuff. The quad core makes a big impact when encoding videos or compressing files.
For example, turning on a computer (SSD of course), opening chrome, Photoshop, watching YouTube videos and turning off the computer, will be faster with the dual core. Agree?

1370 is less than 9% above 1260. Not perceptible outside of benchmarking, I expect.

The Q9650 is on an unofficial supported CPU list for the Q35 Express chipset: Access denied

Good luck.

There is guy on youtube who does a lot of vids about upgrading DElls he might have something about the old 775 series PhilsComputerLab

Another guy using q6600 and gt1030 on old dell
YouTube

https://www.youtube.com/watch?v=fIJb2YteWyY

The safest way is to fully identify manufacturer & model of motherboard & find its specifications:

- open computer case
- observe mobo for any identifiable strings & try to find them, or

- take a snapshot of mobo without cables etc
- use google picture search to find it, or

- CPU-Z can identify some mobos directly - see Mainboard tab.

For some boards, bios update may be necessary to support 1333MHz FSB procs. And not all mobos have voltage regulators suitable for quadcores, see its HCL. Condition of capacitors near socket (should not be leaked) also takes into account.