If i may ask, did your skystar 2 give you problems soon after it's original installation?
If the answer is yes then your motherboard
may be your problem. Some newer motherboards have trouble delivering 5volts over the pci bus. This partially has something to do with the newer pci bus spec and some motherboard manufacturers faulty implementation of the 5volt legacy standard. Many Asus boards have this problem as i found out the hard way. Like i said, your motherboard may be the problem here but there's also a good chance that your problem lies elsewhere (like having a defective card).
A cheap or semi-faulty powersupply can cause problems sometimes but i suspect it is not so in your case. I too had a problem with a new generic powersupply and dvb-s cards. I destroyed 3 motherboards and two excellent sticks of ram before i finally figured that they were all dead. The funny thing is the that most of the motherboards and new powersupply worked fine together without the skystar, and the motherboards and skystar worked fine with my older powersupply. But once i mixed all three all hell broke loose. I was lucky i didn't destroy my skystar2 version 2.3p, a rare and excellent card. This happened recently when i decided to do some minor upgrades, and thought i was dealing with faulty pci bus voltages again (how wrong i was !). Figuring out what happened exactly took a very long time...
I've blown a lot of money in computer parts while pursuing the dvb-s hobby
Unfortunately i cannot advise you about the skystar 3 or twinhan 1025. I do know that the 1025 is a very compatible card and many users seem to be perfectly happy with it, but i don't believe it has any special features over other twinhan cards that are worth mentioning.If you cannot find further info here maybe try a google search, and perhaps try googling the happysat forums while you're at it
