What is the effect of an "ultra vires" transaction as far as the company and its directors are concerned?

Effect of an ultra vires transaction:

 
The company and its Director's shall do all activities within the power of Memorandum and Article of Association any transaction beyond the power is "ultra vires" and the transaction will not bind the Company, effect of an ultra vires transaction relating to the Memorandum and Article of Association are as follows:

1. Transaction beyond the memorandum.
2. Transaction beyond the article of association.
 

Transaction beyond the memorandum:

The transaction is ultra vires and void. It will not bind the Company and the Directors will be personally liable. 

Transaction beyond the Articles:

The transaction is also ultra vires and Directors are personally liable, but if the transaction is incidental or non-sequential then the transaction will be valid and binding on the Company.