For a beginner, you don't need a PC other than the PC you started this thread with. You can use the 3k as additional capital when you lose the other capital you have, or you can use it to pay rent for a short while.
I'll leave the tech stuff to those better qualified. I was advised not to clutter up my trading computer and this was really good advice. Nothing but what I need for trading and data work on it.
Based on your description of your intended usage, your set up will be overkill. Unless you're looking to move around large datasets for quantitative research the RAM is too high, but if you did want to do that, your storage will be too low as the data gets BIG. I'd advise you to forgo the Xeon and go Ivy Bridge, I don't know if your programs are multithreaded, but you might benefit from turning hyper threading off if they aren't.
Still out of my mind why people buy so powerfull machines where any gamer can game basically few times one game. All you need now is like 4 cores, like 16GB memory max fast one DDR4 and speedy SSD or M.2 and that's really it, all else is very very optional.
I run my trading setup on a HP Compaq pro 6300, i5 3470, 8 GB of DDR3 and an SSD. You can buy this refurbished for maybe $150 and it is all you need as long as you aren't running very heavy trading software. I am running MultiCharts.NET (9 charts), Rithmic Trader DOM (3 instruments) and some chrome web pages and my CPU usage nevers gets over 30% and RAM usage never above 50%. A more expensive machine wouldn't make me any more profitable. I am not a gamer so i don't need anything more than what i currently have.
If you are not running Linux, you should DEFINITELY isolate your trading to a separate computer that you do not use for web browsing, email, or messing about with this app and that app. I am amazed, as a former WinDOHs user who left that camp mostly due to security concerns, how unconcerned most traders are with security. WinDOHs BY DESIGN is open to attack. Not attack so much as "Welcome, just walk right in and make yourself at home". MS deliberately left a back door to your system and by accepting the EULA you are acknowledging that MS has the right to do whatever they want to your system whenever they feel like it for any reason or for no reason at all, without your consent or even knowledge. Do you really trust them to keep that back door secure? MS gets hacked all the time. Or they did. Maybe they use Linux or Unix servers now, I don't know. Anyway anybody who is in their system can very likely get into yours, given sufficient time and talent for digital mayhem. There is very poor enforcement of file privileges. Well, you may as well say they aren't even there. Malware is such a concern with Windows that it is considered foolhardy to not run an anti malware suite even though it causes a performance hit. (Most Linux users don't bother.) Windows is also full of other potential exploits that are continually being discovered by hackers because the source code is secret and not available for public review and experimentation the way Linux source is. When an attack is discovered, a patch for Windows is released in ....? A patch for Linux is released sometimes in hours, even minutes. This is because every user is a potential developer. Secret source code is VERY BAD SECURITY. You don't know what the hell is in there. Nor does anybody who knows enough about programming to do anything about it. Linux is designed around the concept of root and ordinary users, and if you do not have root privileges, there isn't much you can do to the system even if you manage somehow to break in. WinDOHs isn't like that. "Admin user"? What a joke. Nevertheless, please do not log in to your admin account when you don't have to, don't be online if you can help it when you do, and log off ASAP. So you are already a bit crippled for security just running that OS. But there is much you can do to minimize your risk and reduce your overall chances to practically zero of being successfully attacked and ripped off. In security you as a computer user are your own worst enemy. The less mucking about you do with your machine, the better. Install only what you must install in order to trade, and only verified downloads from trusted sources. Does that make you safe? No, but it makes you less at risk. You might want to do any online banking on this machine, too, and not on the one you play games on or websurf on or open files on. Every time you click on something, you are allowing code to do something. Generally, you do not know what that something is, at least in the details. Does that sound dangerous? It is. The less stuff you do and the less you click stuff and run stuff, the more secure you are. Of course all the other standard security precautions should be taken... good quality passwords, for instance, and changing them regularly. If it is a password that you can easily remember, then it is a password that someone who knows a lot about you can easily guess. Maybe not outright, but by using your personal data and history as seeding for a dictionary or brute force attack. Selecting passwords is not a time to prove to yourself how clever you are. It is a time to pick random characters and string them together in a random manner and write them down and hide them securely. Don't use the same password for more than one account. Yes that is such a PITA when you can just take your address and drop all the vowels and insert symbols or numbers in some logical and easy to remember order, or use the first letter of every word in your favorite song lyrics, or the name of your first dog and the address of your first school, or the license tag from your first car or your bosses phone number or whatever. Don't do that. Securitize. Randomize. Do I even have to tell you to not trade on a laptop or tablet on someone else's wifi connection without a VPN? If you are on WinDOHs, do your very best to keep your virus definitions up to date. They never are up to date, of course, but do the best you can. Don't leave it up to your antivirus software to do automatically do that, or WinDOHs. I would check for updates every day before market opens. Then after update, log on and start your day. Bottom line, yes, no matter what sort of trading you do and what sort of hardware you put together to do it, just trade on it. All other activities belong on another computer. Be safe. Talkin bout your MONEY here.
While I am personally NOT a fan of HP computers, a refurb is a great way to get a machine on a budget that you can trade on. Even if you have to upgrade it yourself with more RAM or a small boot SSD and a graphics card, there are lots of cheap options out there. I am running a lightly modified Dell Optiplex refurb, myself, for trading. And you can get by just fine on mediocre specs if you are not doing serious data crunching and algo trading. The main thing is to be able to support the spread of monitors that suits you, and never have self throttling or freezing up from overheating.