So I recently started working with DAWs and I use digital instruments 99-100% of the time and I recently purchased Sylenth1 and have been having problems. I suspect it's the sound card, I have an onboard one and am looking for a bit better one. Any ideas?

Welcome to the forum ksned.  This is a common question (in fact there's a similar thread going on right now), and you will receive a lot of suggestions.
 
The best place to start is with your budget, and the connection you plan to use (USB, Firewire etc).  At around the USD100 level you will find external USB soundcards from folk such as Focusrite that will probably more do than do what you need, as well as including a couple of line ins should you wish to attach a mic or guitar input.  As you move up the budget you will find the RME Babyface (that's where I am now) that have better A/D converters, SPDIF and lower latency, and an increasing number of inputs/outputs.
 
I don't know exactly what your requirements are, but I would *suggest* an external USB soundcard, with 2 mic/line ins, a pair of balanced outputs and a headphone output.  Something like the Focusrite Scarlet 2i4 maybe?  That would certainly be a world of improvement over the stock audio card in the pc.
 
<EDIT> for poor grammar, spelling and other stuff that makes Strummy mad!

'SOUND CARDS' have given way to usb or firewire interfaces.
 
do a google search on pcie cards, versus usb interfaces,
that will give you an indication of what's available and how much it will cost.
 

Actually, before you do any of that stuff above it would help if you add your system specs to your signature as well.  That will tell us your pc configuration, DAW version and other gear you are using.  If you're running an off-spec PC then the soundcard isn't really going to help much.
 
Also what are the problems you are seeing?  Drop outs, crackle/pop sounds - those could be the soundcard.  Complete system freezes are more likely to be system (ram/processor related).
 
btw, I have a fully working SPS-25 that I don't need following the RME upgrade.  It will work with W10 with a slight dodge to get round the driver signature and is otherwise a great unit to start with.

The largest plugin I have is Sylenth1 and it is the only one that seems to cause the problem. I use FL Studio 12, and at random moments when the VST is incorporated in the project it will freeze or stop playing sound shortly before or after showing a pop up saying there was a violation of the fruity wrapper. The specs I can remember are it has an i5 6600 processor, 16gb 2666 memory (I think vengeance). And I am not 100% sure on what type of connection I want, likely a USB connection. I have contacted Lennar Digital though and they said it's likely related to my sound card or the system. Thanks for the replies and help!

Mind if I ask you what you're doing on this forum? Shouldn't you be on the FL forum?

I couldn't find any help on that forum so I came to the second most knowledgable people xD

ksned
I couldn't find any help on that forum so I came to the *first* most knowledgable people xD

Fixed that for you.

just messing around geez... most hostile too? anyways the inquiry wasn't about the DAW it was about the sound card...

There are a ton of options available. It comes down to how much you want to spend on it and what you need it to do. The Focusrite would probably be the best bet for you if all you're doing is in-the-box stuff as most of the processing will be done by the computer itself. This is what I'd look at: http://www.sweetwater.com/store/detail/Scarlett2i2