RAM Bottlenecking Game preformance?

[Kalkmann]

I have a EVGA GTX 780 ACX and a i7 2600k at stock speed and stock cooler.

But in most of games GPU usage is very oscillating and low (like 30~75%)

I dont think that my 2600k can bottleneck a 780... and after reading some forums i've seen that it can be caused by the some RAM problem.

- I have 2 Kingstom sticks (4gb/2gb 1333mHz) and 2 Megaware sticks (2gb/2gb 1333mHz)

Different RAM brands can be a problem? even with the same DRAM?

I also have
- ASRock B75Pro3m Motherboard
- Corsair TX750M PSU
- 5400 RPM HDD 1Tb

 

[wildfire707]

That is unusually slow memory for such a high end system (admittedly 3 years old, by the looks of it). Running two banks of memory (4 sticks on this system) will slow it down slightly, but your biggest problem is the size of memory.

To run in dual channel mode, (where both sticks of memory in a set can be accessed simultaneously to double memory bandwidth) you should run identical memory modules in both banks in a set. There are many reasons for this, but that seems to be your biggest issue from my point of view.

Given your system description, your computer is likely running the memory in single channel mode. This means that the CPU can't access the memory fast enough to keep it busy and system performance will suffer.

If this is the problem, I would recommend that you get an 8GB memory kit consisting of 2 x 4GB units at either DDR3 1600 or DDR3 1866. Something like the G.SKILL Ares Series 8GB (2 x 4GB) kit F3-1866C9D-8GAB would work fine and is normally $85.

 

[Kalkmann]

That is unusually slow memory for such a high end system (admittedly 3 years old, by the looks of it). Running two banks of memory (4 sticks on this system) will slow it down slightly, but your biggest problem is the size of memory.

To run in dual channel mode, (where both sticks of memory in a set can be accessed simultaneously to double memory bandwidth) you should run identical memory modules in both banks in a set. There are many reasons for this, but that seems to be your biggest issue from my point of view.

Given your system description, your computer is likely running the memory in single channel mode. This means that the CPU can't access the memory fast enough to keep it busy and system performance will suffer.

If this is the problem, I would recommend that you get an 8GB memory kit consisting of 2 x 4GB units at either DDR3 1600 or DDR3 1866. Something like the G.SKILL Ares Series 8GB (2 x 4GB) kit F3-1866C9D-8GAB would work fine and is normally $85.

my motherboard supports 1600 mHz DRAM, but what about the 2600k that supports 1333mHz? should i overclock the CPU if I got a 1600mHz or something?

 

[wildfire707]

I am currently running DDR3 1866 just fine on my 2600k system using an ASUS P8P67 Pro motherboard. The XMP profile of the memory is being used, so I didn't even have to go into the BIOS to set it to that speed. Your ASRock motherboard can only run it at 1600 Mhz, but if you get a newer motherboard in the future it will be one less upgrade to do.

You don't have to overclock the CPU to use faster memory. I am curious as to why you payed extra for an unlocked CPU if you are not going to overclock it? - Ah, never mind, your motherboard does not support overclocking (as geofelt pointed out).

 

[geofelt]

Ram speed is not an issue with modern intel cpu's
Here is an article in ram scaling for sandy bridge.
You are looking at perhaps 2-3% difference in fps or app performance.
http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3

Test your ram with memtest86+. There should be NO errors.

If I had to guess, I think a 54oorpm hard drive is likely the culprit.
They are designed for low power usage in laptops not for performance.

See if you can't change that out for a ssd. Everything you do will be so much quicker.

Another check would be to try these two tests:

a) Run your games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.

b) Limit your cpu, either by reducing the OC, or, in windows power management, limit the maximum cpu% to something like 70%.
Go to control panel/power options/change plan settings/change advanced power settings/processor power management/maximum processor state/
This will simulate what a lack of cpu power will do.
Conversely what a 30% improvement might do.

You could also experiment with removing one core in the bios. This will tell you how sensitive your games are to the benefits of many cores.

If your FPS drops significantly, it is an indicator that your cpu is the limiting factor, and a cpu upgrade is in order.

It is possible that both tests are positive, indicating that you have a well balanced system, and both cpu and gpu need to be upgraded to get better gaming FPS.

Your B75 motherboard does not permit CPU overclocking. Your 2600K can do better with a Z77 motherboard.