To exit China you just need your pasport and visa as a foreigner.  But if you do have the residence permit and the Temporary Registration of Address for Visitors Form, eventhough it is never rquested, I would still carry it just in case.  Now, be aware tha in swome types of visa (like Z visa for example), the residence permit becoms actually your visa.

Addl question, what if my X visa Duration is 000..is it its up to me how long I can use this to stay here in china?for example 1 year?

OK, with full information now I can give you an answer.  A student visa is given for you to enter China to study for a period of over six months normally. less than that it is suggested you get a business visa.  On this type of visa, the validity is clearly indicated, normally over 6 months.  The number of entries is normally one only.  The "STAY" is shown as "000" with a strikeout line accross the center of the zeros.  This is because within 30 days of entering China, a student must go to PSB and request a residence permit valid for as long as his/hers studies last.  This permit will take over now and work as your visa. and it would be wise to request it issued with multiple entries, so you ca either travel or visit back home.   And in your particular situation, yes, you will need a residence permit to exit China.  If you failed to get a permit when you enter China, you have been staying here illegally.

I came on a tourist visas and registered at PSB and asked if I should have a resident permit. they told me no, all I had to do was tell them where I was. I only had my passport with visa to carry.

GreetingsTed:  different visas have different requirements.  A tourist visa, eventhough many use it to be in China for years, (with the run outside China's borders when the stay is over to renew it), it will not warrant you a residence permit unless you meet a criteria set by them that somehow you do have a reason to be in China for longer than a "visit", like for example marriage to a Chinese national.  

( it would be wise to request it issued with multiple entries,)   Residence permit always work as a multiple entry visa, you no need to make a special request for that..I have residence permit which has been issued for working here when I came here on Z Visa and there is nothing mentioned on it about number of entries..but every quarter i use to visit other countries for my official work..there is only validity of Residence permit..

If yours do not say a thing about entries, I have had mine issued with 1 entry, 2 entries and now with Multiple Entries ("M").  And they had a different cost too, the more entries, the higher the price.  And I do know a couple of fellows (one from Australia, one from England) who also had different number of entries at a different cost.  By the way, a one year multiple entry for a USA citizen was 970 yuan on the last try.

Student visa allows you to study in China. If you enter China in student visa you have 30 days to change it into resident permit. Now be reminded that when you get the resident permit under student visa it means that you can't exit China if the migration officer in the airport suspects that you probably didn't settle your university fees. This happens when the university allows you to study and give you resident permit so that you can pay the fees in instalment. Now the universitlies don't allow this to happen. So if you have student visa and resident permit you can only leave when you settle your fees What if you get the permit and run away without paying the fees in case they allow you to pay in instalment?