Hello. Looking at the feasibility of upgrading my processor. Currently have a Dell 1558 with a first Gen I7 Processor the Q820 for mobile devices. I am curious what the max supported processor is i can put into the device and what real improvements there would be over the current processor.
You're laptop has a processor that is a few generations old. I'm assuming this is the processor you have: http://ark.intel.com/products/36547/Intel-Core2-Quad-Processor-Q8200-4M-Cache-2_33-GHz-1333-MHz-FSB ARK | Intel® Core™2 Quad Processor Q8200 (4M Cache, 2.33 GHz, 1333 MHz FSB) or maybe this one: http://ark.intel.com/products/40816/Intel-Core2-Quad-Processor-Q8200S-4M-Cache-2_33-GHz-1333-MHz-FSB ARK | Intel® Core™2 Quad Processor Q8200S (4M Cache, 2.33 GHz, 1333 MHz FSB). If your laptop has a socket so that you can swap the processor and if the BIOS of your laptop supports the "upgraded" processor, you could theoretically swap processors. You would have to get a processor of the same generation as the processor you have. You would want a processor that doesn't have a higher TDP. You might find one that has a faster clock frequency and bigger cache. But I wouldn't expect to get a really big performance boost.
Computer performance has come a long way since your computer's generation, so you probably would not be happy with upgrading your processor to another processor from the same generation. If it was me, and my computer didn't perform at the level I needed, I would buy a new computer instead of thinking about upgrading the processor.
The only processors that were faster and compatible with the cpu socket on your laptop, were the i7-840QM, i7-920XM and i7-940XM. I do not think that these processors are readily available, unless you can find them use on Ebay or taken from old laptops.
Is it worth upgrading? I don't think so. The performance gain is not worth the trouble.