"Shwd ych chi?" is how people speak in the south of Wales, "Sut dych chi?" is a more standard or northern pronunciation. In many parts of the north people would also say "Sut dach chi?". The pronunciations aren't quite the same. In south Wales "s" is often pronounced like English "sh" (or Russian "ш") when it is adjacent to an "i" sound, and "u" in south Wales is pronounced like "i" (although in the word "sut" the pronunciation is different, but the effect on the "s" remains). In the south, "y" in a final syllable is also pronounced like "i", but in the north "u" and final-syllable "y" are pronounced much like Russian "ы". So, the first phrase would be pronounced /ʃʊd ɪχ χi/ ("шуд их хи") and the second, spoken by a northerner, /sɨt dɨχ χi/ ("сыт дых хи").