GPU help

Considering the age of your components, you really should build a new rig.
When was the last time you bought a new Power Supply?
If you buy a new GPU and the PSU can't handle it you might lose the entire computer.

if you're patient you could wait for AMD VEGA likely to be the best bang for the buck (soon in some months max. 6? from now i guess) or get yourself a cheap RX 480 / RX 580 8GB - those are practically the same GPU's and since driver updates better than a GTX 1060 6GB; current best bang for the buck would be RX 470 4GB / RX 570 or if it has to be NVidia GTX 1060 6GB - don't settle for less ... btw. you're cutting it close with the CPU but probably still good for most games

PSU - Power Supply required best ~ 450W or check here *

Build a new PC, yours will hold back any modern GPU.

I think GTX 1060 6GB is much better.

I have the exact same CPU. Contrary to what most people will say, I think it's a half decent CPU to be honest. It won't run every game maxed out, but definitely a good medium-range CPU. I have a R9 380x and my CPU bottlenecks, but I'll be upgrading soon to remove this issue.

Your first concern is your PSU, to be honest. If you want to upgrade your GPU, for the love of your computer components, upgrade your PSU if you haven't already, or if you aren't confident it's good enough. Remember - wattage alone is no indicator of a good PSU. Look for something with decent wattage, high quality, and not some shit brand like Rosewill (personal experience here).

I bought a 80 Plus Certified EVGA PSU and damn, I'm not regretting this decision. I feels right, it works great, and it's cool and quiet. Plus it's fully modular. But yeah, bottom line is, lots of people will tell you you need to upgrade your entire rig. I say upgrade what's necessary if you can't afford to build a new PC, and you should be fine. Your CPU can wait a bit, but the PSU can fry the entire rig.

from the sounds of the type of gamer you are based off description, you'll probably be fine with your selection of 1050ti or if you can go with the 1060 6gb if you can push that extra little $ into it. like others said you'd be limited on cpu the most after that though and this would probably be the last time you can get away with just a gpu upgrade. next thing i'd do later on after this upgrade is a full rig upgrade minus the gpu replacement you decide to go with this time.

tomshardware Best Graphics
http://www.tomshardware.com/t/graphics/
http://www.tomshardware.com/reviews/best-gpus,4380.html

$99.9 AMD Radeon RX 460
$139.9 GTX 1050 Ti
$244.9 RX 580 4GB

what for a psu and how much watt does it have?
for 200€-300€ you can get easely a new RX480 or GTX1060 6GB

An RX 460 for that CPU. Maybe a 470, but it may be bottlenecked. They are relatively cheap and can even last another at least 2 years comfortably if you can manage with low-medium settings.

It all depends on which games you want to play and you can't atm (usually a casual gamer doesn't play most recent games)

u should add one more 8 GB RAM

1050 won't need better PSU, they don't have additional power cables but only use pciexpress port for power.
if you opt for 1060 check what you have in psu department and think of seasonic or evga or something like that
rest of your computer is old, but it's okay and adding additional 8 gigs of ram or ssd would be everything you need.
your motherboard does not support newer i5 cpu's so you'd need to change everything and there's no need for that yet, honestly (it's great if you have the money, but if you're on a budget, this computer can serve you for additional 2-3 years at least).

use speccy to find out what components you already have

I suggest you this card a beast in 6 GB.
https://www.amazon.com/dp/B01KCWZ2EO/?tag=pcpapi-20

I bought myself a 1050 Ti for Christmas in the Black Friday sale on Amazon. I'm really happy with it. I can play games like GTA V and Skyrim Special Edition on pretty much max settings at 1080p and that is good enough for me. I stuck it an older computer though and I did have to buy a new PSU which was an unexpected expense - my old one didn't have the power cable that the GPU needed.

If you really have a 250W PSU and considering the age of the CPU I would recommend RX460 (a model without additional power supply plug as your PSU probably doesn't have one) or GTX 1050 at best. A good and cheaper alternatives would be RX550 or GTX 750Ti.
edit: as others said, adding 4-8 GB more RAM would help as well

If your power supply is, indeed, only 250 Watts, you will want to upgrade that. The minimum recommended rating for a 1050 Ti is 300 Watts. Plus, those old Lynnfield i5 CPUs have a 95 Watt TDP, so you're likely going to want a fair bit more than 300, ideally. Plus, it sounds like you have a pre-built computer, which often doesn't include decent power supplies, even given the wattage. One thing to look at is how many 12 volt rails it has and how much current it provides on those rails. If it's a multi-rail system, you're likely even worse off. These days, you can get good power supplies for not too much, but I'm not sure about prices in Europe. A couple years back, I got a 450 Watt 80 Plus Gold Corsair power supply for free after rebate. $20-$30 is not an uncommon price range for that caliber of a PSU.

The next issue, as others mentioned, is the bottleneck. My desktop has a CPU from the same era, a Xeon X5650, but it has six cores, hyperthreading, and it's running at 4.2 GHz. In some CPU intense games that require good single-threaded performance, like Arma 3, I would still bottleneck a GTX 1070. Unless you overclock your CPU to ~3.6 GHz (which is attainable by most 750s), you'll end up bottlenecking a GTX 1060 or RX 480. That said, it's going to depend on the game, and games that have large textures or ones that you play at a high resolution could very well be GPU limited. But games with a lot of AI or NPCs may be limited by the CPU. Either way, in most cases, you'll be fine, and I don't think a GTX 1050 Ti should be bottlenecked much. (I remember reading someone was running a GTX 780, which is more powerful than a 1050 Ti, with the same CPU as you without any noticeable bottlnecks, although I can't recall if he was overclocked).

Go with a gtx 1060 6gb don't go with a gtx 1050 because you could find a older gpu with better performance. You can compare gpus here http://gpuboss.com/

Considering your PSU, I'd suggest waiting for the GeForce GT 1030, which is rumoured to be released in a few days. In terms of power consumption it won't be much different that the GT 610, and although it will be quite weak compared to other modern cards, it will still be about 10x as powerful as the GT 610 and should still be able to play modern games, even if you'll have to compromise on settings. I think it will be enough to play some games at high settings at 1080p, certainly those from a few years back. Considering your current card, I'm sure you have some catching up to do.

Start saving money for a bigger upgrade later.

i have a similar setup. just bought the 1070. a bit more expensive. but very good :D

Your components are fine. You won't be able to play everything at 60FPS in full detail but then again so can't 99% of gamers.
All you need is a new GPU, either AMDs latest or Nvidia.
You should replace your PSU as the older they get the more prone to failure they are. A 500W is totally sufficient, go for a Gold or Platinum rated one as they have better components and sometimes a better and longer warranty.
Personally I'd get an AMD unless you do multi-monitoring a lot as Nvidias use a lot less power then.
Edit: Damn, couldn't find the vid, sorry ;)
Edit: Dependant on the price, go for a 1050Ti, 1060 6GB or AMD 470/570
Don't get a 1060 3GB version, they are castrated in memory and performance.
Edit: Which PSU vid: https://www.youtube.com/watch?v=LFx26E_DBUY