Questions about graphics cards and my experience researching

[Brado11]

I'm a semi-competitive gamer and mostly play League of Legends which isn't very graphics requiring but when I play other PC games such as Dragon Age or Skyrim etc. the performance is rather lacking.

My current specs are:
MB:GA-78LMT-S2 (PCI-E 2.0x16, PCI-E 2.0x1, &PCI 1.0)
CPU: AMD FX-4100 Quad Core 3.6Ghz
GPU: Nvidia (EVGA) Geforce GT610(1 gb ram)
RAM: 8GB
PSU: Unknown (Is there a way to check without opening my case?)
Windows 7 64-bit

I have been wanting to update my GPU for a while and have my eyes on the Nvidia Geforce gtx 750 ti is it compatible with my system PCI slot wise?
What other viable graphics cards are there <200$ ?
What are some of the main factors that affect performance of graphics cards? (their memory vs. clock speed etc.) ?
What's the difference between Zotac and EVGA? Is either gtx 750 ti better? Are they both considered Nvidia?
What are the power requirements for the gtx 750 ti? 300w?
Are there any visible misconceptions I have based on my questions above?
Any answer is very helpful thanks in advance guys =D

 

[Ankit Bandral]

yes gtx 750 ti supports your system. You should buy r7 265 instead of gtx 750 ti which is also of the same price range but it requires a 6-pin connector and a good psu. the only way to know about your psu without opening your case is by visiting your pc supprt site and typing your pc model no. If you have a low wattage psu then you should buy gtx 750 ti.

 

[Brado11]

yes gtx 750 ti supports your system. You should buy r7 265 instead of gtx 750 ti which is also of the same price range but it requires a 6-pin connector and a good psu. the only way to know about your psu without opening your case is by visiting your pc supprt site and typing your pc model no. If you have a low wattage psu then you should buy gtx 750 ti.

http://gpuboss.com/gpus/Radeon-R7-265-vs-GeForce-GTX-750-Ti

According to that they are about equal but I would rather go with the nvidia because it's what I trust.
What's a 6 pin connector? and I will be checking my PSU soon but am short on time right now.

 

[Ankit Bandral]

6-pin is a cable to power the graphic cards needing more than 75 watts. if you want to go with nvidia then you should get gtx 750 ti. buy evga gtx 750 ti http://www.newegg.com/Product/Product.aspx?Item=N82E16814487025