[-l] Launch Config setting possibilities

[gjgjg]

Hi, started mining LTC and others using Cudaminer with my GTX560ti card. I tried following the settings in mining hardware wiki page (C 1 -i 0 -H 1 -l F14x16), but I get an error: 'result does not validate on CPU!'
When using auto setting i get around 120kh which is nice and is quite stable. When I run the above settings I get 500khash - but then the error appears so im obviously interested in seeing if can sustain 500kh, but i presume its not feasible

Im led to believe the [-l] setting is the one causing the trouble, but rather than trial and error, does anyone know what the different possibilities are for this setting? Does it have to be multiples of anything similar? Like 28 x 32 or 7 x 8 for example? or can i just put random numbers in there (within reason ofc)?

Thanks and sorry for noob question

FYI I have an old AMD phemon Cpu quad core (10ghz ~)

[gjgjg]

A Nvidia card shouldn't be able to hash at 500 khash/s

thats what i assume, but thought id check with the experienced around here before discarding as an anommoly. still would be great to see what ranges the -l i can try