is there any technical difference between Solid and Stranded RJ45 network cable??? any reason I should prefer one of them than the other one? thanks

The obvious answer is yes, one is a single, solid piece of copper. The other is made up of multiple smaller strands. But I suspect that's not the exact question you wanted answered. I'm thinking you really want to know if there's any kind of performance differences. As far as I know, there's not. Stranded however, is more supple and flexible than solid core and is better for patch cables than solid. I will say this. We use both here where I work and stick to solid core for main pulls through conduit and stranded, as I mentioned above, for patch cables. One thing you don't want to do is mix RJ-45's with cable types. Which is to say, don't put a RJ-45 for stranded cable onto a solid core cable and vice versa. The ends are different and this can cause connectivity issues because the cables themselves often won't work properly when the wrong RJ-45's are used.

Curt, Thank you for your reply. basically, I am going to run a 20M network cable through trunking to connect a PC to the main switch. As you explained, I now beleive a solid cable is more suitable. and I use stranded cable for short patch cables. I only thought stranded cable might be a better option as the cable has to bend a few corners. I also didn't understand when you said "don't put a RJ-45 for stranded cable onto a solid core cable and vice versa". are not solid and stranded both 4 pairs cables?? thanks

What Curt was saying is the internal make up of the connector, because the number of strands are different within the two types of cable the ends that go on them have to match the cable it is being crimped onto...HTH PS Some places may try and sell you a connector that will do both but I have had little luck with them and simply keep both types for each app. Keep the old stuff running