Question Upgrading my gaming rig

Hi, all. Would love some help figuring out how to upgrade my current gaming rig. The specs are:

Motherboard: Gygabyte P55A-UD5
CPU: Intel i5 750 @ 2.67 GHz (4 CPUs)
RAM: 4GB DDR3 @ ~1300 frequency
GPU: Sapphire Dual-X R9 280 3GB
PSU: Don't remember, but it's from a really good brand, although at lower capacity than what would be recommended for this rig from other manufacturers. Never had a problem with it, though.

Anyway, this rig had been good enough to run almost every one of the latest triple-A titles at full graphics at 1080p without a problem, though the Witcher 3 is proving to be way too much for it to handle and I'm afraid the next upcoming titles I want to play will probably not run very well, either. Already tried all kinds of tweak guides, different graphics settings, overclocking the GPU and it still performs poorly.

Performance monitoring showed my four cores were running at maximum for this game, so I tried my hand at CPU overclocking too, but botched that miserably as the guides I read for similar setups resulted in my PC becoming unable to power up at all, and the Gygabyte Easy Tune tool simply does not install on my machine for some reason.

I realize the RAM is relatively low (even lower than the minimum requirements for the game), but I'm not sure if that's what's bottlenecking me the most, or if it's the weak CPU.

I'm not a complete newbie to PC hardware, but my knowledge is limited on certain topics, like whether my motherboard would still be compatible with current gen CPUs. I don't particularly fancy having to buy both a new CPU and a new motherboard. If possible I'd like to upgrade the CPU with something relatively low-budget, but I have no idea what kind of products I should be looking for.

Would appreciate any insights on the matter, so I can spend my money wisely.

Thanks in advance.

 

Really? My CPU is like 5 or 6 years old, I was afraid it wouldn't even be good enough to keep up with the GPU. The MSI afterburner app shows that all four cores are running at peak while playing The Witcher 3. Or is that normal and not really a sign of the CPU being too weak?

Anyway, my OS is a Windows 7 x64.

Also, is there any specific RAM types that won't fit into this motherboard, or is any DDR3 RAM ok?

 

What I find strange is, that task manager often says the game is using up like ~2.9 GB RAM, and never goes past that, even when nothing else is using up memory. I know Windows itself uses like 0.5 GB, but that still leaves some missing.

I have already changed that one setting, so that Windows realizes that there are 4096 MB RAM available, but the game never goes past using up ~2.9 GB.

I already looked at the motherboard's manual and all it says is to check motherboard manufacturer site for compatible RAM. I find all these technical terms extremely overwhelming, as I can't tell what is relevant to hardware compatibility and what isn't.

Do you have any suggestions for a good 2x4GB DDR3 RAM sticks set?

Also, I assume that when I get a new set of RAM sticks, I should remove the older set, due to being different brand/frequency than the new set?

 

Alright, cool, thanks for the help, man!

 

Ok, so I bought a new pair of RAM sticks. Same brand, same frequency, same timing, except they were 2x4GB capacity, instead of the 2x2 GB I already had.

Installed the sticks. Had to install the new sticks in the slots the old sticks were, and installed the old sticks in the other dual channel that was previously unused, doing otherwise would not allow my system to start, for some reason.

BIOS recognizes all the RAM, DxDiag too, I changed the settings under Window's System Configuration > Boot > Advanced Options > Maximum Memory to 12 GB, but the game is still only using ~2,4GB and running like crap.

Any idea what the issue here could be? It is obvious the game should be using more RAM, since the minimum requirements are 6 GB, yet for some reason it's not.

 

Well, the Processes tab in Task Manager shows 37% of physical memory usage with both The Witcher 3 and Firefox running simultaneously, at ~2,5 GB and 250 MB usage respectively.

The Performance tab lists the following:
Physical Memory
Total: 12283
Cached: 2456
Available: 7725
Free: 5490

I can't figure out what the problem is. Doing google searches on the subject doesn't get me anything, either.

Also tried simply unchecking the Maximum Memory checkbox in the msconfig settings and restarting again to see if something changed, but no luck.

Edit: Just ran a mdsched.exe test, no errors were found. No idea what's going on...

Edit 2: even going to the game's busiest place where the performance is at it's worst and bumping up the graphics settings, the RAM usage on Task manager shows as being only slightly above 3 GB. Performance is still pretty bad and CPU usage is floating around 70%, so that can't be the reason. This is starting to get frustrating.