Periodic lag/freezing and no max performance?

Yes it could be a software issue; I have no idea about Windows gadgets but obviously they shouldn't be using 4.5GB of RAM.

I assume you are running 64bit Windows, as you have 8GB of RAM installed?

 

Yes I am using 64bit windows.

 

Then perhaps you could try a fresh install.

Before doing that, go in to BIOS and you should be able to check the SMART status - and therefore health, generally speaking - of your HDD, or if not use an app such as http://panterasoft.com/hdd-health/

 

What does this smart thingy do?

 

Bump. I sent my computer to the shop again, we tried replacing the RAM, the motherboard and still same issue. He didn't have another GTX 560 Ti. So he'll get one and we'll test it, I think it's the GPU since everything else has proven to be not the issue.
I also think it may be the PSU. IDK how PSU's work, but IIRC the shop hooked up the 12V1 rail to the GPU ( which, according to the specs on the box of the PSU, delivers 30A ). The 12v2 rail is not hooked to anything, it also delivers 30A. Does this mean that it delivers 60A to the GPU from only one rail? Is 30A enough for a GTX 560 Ti ( not the 448 version btw ) ?. I can't find out how many amperes the GTX 560 Ti needs from google.
Thanks in advance.
P.S The psu is 700W cougar CMX

 

Well then yes, it should be either faulty GPU or PSU, assuming the HDD is healthy etc. Sometimes eliminating components is the only way to get to the bottom of a problem and it is a pain but necessary.

A 700W PSU should be ample for your setup. Let us know how it goes.

 

So, my PSU is supplying enough power to my GTX 560 Ti? How many amperes does my GPU need? I couldn't find that on google.

 

Alright thanks, but is it normal that only one of the 12V rails is used? Like I said, I didn't build this computer a shop did it for me, I was thinking that maybe he's messed up with the connections. When I looked at the PSU, the 12v2 rail wasn't used at all, is that normal? Or the shop has messed up?
Thanks again, appreciated.

 

Take a look here:
http://www.nvidia.com/content/geforce-gtx/GTX_560_User_Guide.pdf

So I as far as I can tell without looking at it, your setup is correct and the PSU is good enough.

Edit: But, obviously, refer to this manual and check for yourself if they have the setup correct.

 

Ok, I got back the PC after many trials to no avail. Even changing the GPU didn't work.
I discovered something. The 12v1 has many cables that are connected to nothing, except one that is connected to some port but the other end is left free. The GPU is receiving its power directly from two pci-e cables coming from this hole-like opening from which many cables come. Does this mean that the GPU or other components may be not getting enough juice?
Thanks

 

I also used the H.D.D health thingy ( the windows app, couldn't find the SMART technology in the bios ). The temperature is 42C, Health is 67% and Drive health : Normal. This good?

 

Bump

 

I really couldn't tell you without looking at it - sorry, that's not much help. If you don't think your GPU is connected correctly, take a look at the user manual I linked to a few posts back and check for yourself. I doubt it though, as the shop that built it should really be getting this right.

HDD health sounds normal.

 

I used HD Tune pro, it tells me that End to end error detection failed, with the threshold reaching 99. Could that mean anything?

 

Google that for more info - depending on the program you use, the reported error may or may not indicate a problem with your drive (ie others report similar results as healthy). The number on the end is the one to pay attention to - 99 99 99 2 or whatever, I think.

 

Current : 1
Worst : 1
Threshold : 99
Data : 145
I checked the HDD of a friend, who has the same HDD ( a seagate too ) but he has 500 GB while I have 1 TB. His wasn't failed, it was ok and the following :
Current : 100
Worst : 100
Threshold : 99
Data : 1

 

Yeah, like I said, I'm not overly familiar with the specific tests so you're going to have to Google for more info on how to interpret the data and then decide what to do with that info.