Rubenis

did you release the pcie lock?
dont pull it too roughly or the entire pcie cover will come out, then you have a big problem

Do the 775 to 771 mod and take Xeon - faster clock speed, biger cache, cooler operation and therefore better OC potencial.

Your bros problem is the CPU.
 
Rather than a Q6600, I would suggest a Xeon e5450 or Xeon x5650. Those CPUs are much faster than a Q6600 and are intended to run on a socket 771 motherboard; however, with an easy modification to the socket and a piece of conductive tape placed on the bottom of the Xeon -- together with a modded BIOS the Xeon will fit and work completely in most (not all, but most) mainstream 775 motherboards.
 
The retail Xeons noted above (you do not want an engineering sample for this) overclock all to hell and will go to 4.0-4.2GHz under a Corsair H60 AIO without difficulty. This will add significant power to your bros computer.  The Xeons go for about $25-35 on eBay.
 
If your brother does not already have 8 GB of RAM, I suggest that he upgrade from 4GB to 8 GB of RAM. DDR2 is expensive stuff but it is available off of eBay here: 

http://www.ebay.ca/itm/281705992229

The relevant thread to read is here:
 
http://www.overclock.net/t/1431723/mod-lga775-support-for-lga771-xeon-cpus

And the video to watch on the modification is here:
 
 
 

It works with most mainstream moboards.  Read the thread on overclock.net and determine your mobo's compatibility.

755s have Q35 chipsets, I currently am building a hackintosh out of one and it should support the 771 socket mod. Make sure you have A22 bios revision also.

Do the 775 to 771 mod and take Xeon - faster clock speed, biger cache, cooler operation and therefore better OC potencial.

engineering sample, not supposed to be sold

I got this. 
 
PCPartPicker part list: http://pcpartpicker.com/p/N8JxZL
Price breakdown by merchant: http://pcpartpicker.com/p/N8JxZL/by_merchant/
CPU: Intel Core i3-6100 3.7GHz Dual-Core Processor  ($110.99 @ SuperBiiz) 
Motherboard: Asus H110M-A Micro ATX LGA1151 Motherboard  ($51.98 @ Newegg) 
Memory: Crucial 8GB (1 x 8GB) DDR4-2133 Memory  ($26.99 @ SuperBiiz) 
Storage: Samsung 850 EVO-Series 120GB 2.5" Solid State Drive  ($66.75 @ Amazon) 
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive  ($45.89 @ OutletPC) 
Video Card: Gigabyte Radeon R9 380 4GB SOC Video Card  ($198.98 @ Newegg) 
Case: Cooler Master N200 MicroATX Mid Tower Case  ($34.99 @ Micro Center) 
Power Supply: Fractal Design Integra R2 500W 80+ Bronze Certified ATX Power Supply  ($29.99 @ Newegg) 
Other: Windows 10 Home (64 Bit) - Kinguin ($30.00)
Total: $596.56
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-05-06 09:51 EDT-0400
 

Do the 775 to 771 mod and take Xeon - faster clock speed, biger cache, cooler operation and therefore better OC potencial.

Second hand GTX 660

HD 7770 used or R7 260X depending on the prices.
 
All of those games are more CPU bound than GPU. Dark souls 1 is so bad optimized you will get lags even with high end system.

That's why I said...... "in an ideal world". This ideal world I speak of is where money is no object. So for  now just stick with PCs.

If your going to have a GPU, save yourself the money and get an Athlon X4

i3>FX6300>G3258

it's not recommended to buy a pentium anymore. most new games don't even run on 2 cores. You need to get an i3 or higher.
 
also there is no way i3+h81 mobo is more expensive than 6300.

Honestly man, don't invest into an APU if you plan to buy a GPU anyways.
 
You should be looking to an i3.  H81/B85 + i3 paired with a GPU will be a much better build, and has a much better upgrade path than what you are currently thinking of doing.

PEOPLE STAY CALM NO FLAME WARS PLEASE

get a knife and very slowly pry it between the cooler and the CPU. slowly wiggling it until it pops off!

Well there are not so many games, that uses more than 4 threads, so that makes i3 cpus with high clock speed and great single core performance makes it better on all type of games than FX 6300. And they are same price.
 
About i5 and FX 8XXX - FX is cheaper, but most of the time to match i5 they need to overclocked, that means more expensive motherboards and that makes i5+mobo combo much more closer to price of FX +mobo. About performance - Intel uses more advanced architecture. And that is about it.

source

Check for Xeons and 775 to 771 mod on your motherboard. You will get quad core for about 30-40 dollars and then you can save up/make up by selling GTX 650 for better graphics card.

No ... We need to move the i3 to 4 cores without hyperthreading , move the i5 up to 4 cores WITH hyperthreading , move the i7 to 6 cores with HT ...

"R9 290, the closest thing to a nuclear reactor for your pc" - Austin Evans.

Specifically which CPU. 478 and 775 can be overclocked depending on your board.

I'd go with any Haswell i3 at this price point. Best option out there. Unless you want to look for a used 2500k on a place like reddit hardware swap. They go for around $120 there.