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CPU Bottleneck

Last response: in Graphics & Displays
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December 27, 2011 8:01:07 AM

Hi guys and girls,

I'm currently running an i7 870 (Oc'd @ 3.52ghz) (1156 chipset) with 8gb of Ram, 6990 + 6970 in trifire.
I can get most things running at full settings and gaming at 6256 x 1152. I do think that my CPU is causing a bottleneck though.

Does anyone have any suggestion on ways to ease this problem without upgrading or alternatively... if I did have to upgrade, what chip would be best?

Sadly money is a barrier so I dont want to go up to a new 3930k chip... although that would be nice.

I've also taken a look at 2500k and 2600k chips... these are newer but I wonder if they are much different in performance compared to my i7 870.

--------------------------------------------------------------------------------
Case = Bit Fenix Collusus
MB = Asus P7P55D-e Pro Chip = 1156 i7 870 Oc'd 4ghz, Cooler = Noctua NH-D14 Cooler
MEM = 8gb DDR3 Ripjaw @ 1600mhz (single channel)
GPU = VTX3D 6990 + 6970 Tri Fire Monitors = 3x Dell SP2309w in Eyefinity @ 6368 x 1152
Drives = 2TB WD Caviar Green + 2x 1TB Samsung F3 + 320gb Seagate Barracude (for backups) + LG Bluray writer + LG DVD writer

More about : cpu bottleneck

December 27, 2011 3:23:01 PM

I can get most games to play at 6256 x 1152 and the highest settings. Battlefield runs ok but maybe a little slow. If I play Crysis 2, only two GPU's get utilised but I think thats down to the game rather than my machine.

Batman Arkham City however has 50% utilisation on each GPU. My CPU usage does spike highly though. All I get at the moment while playing this is between 10 and 20 fps on max settings. Looking at the forums though I know this game has problems with Direct X 11 at the moment though.... I dont know if a new CPU will boost performance in these games or not though? I know the i7 870 is a little old now.
December 27, 2011 3:32:52 PM

You're running 8GB of RAM on a single channel? Pushing texture and geometry data from DRAM to 3 frame buffers requires a lot of bandwidth, I suggest you start there
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December 27, 2011 4:45:51 PM

You say your chips overclocked to 4ghz, then you say 3.52ghz, which is it really?

You could answer the question yourself. Run a benchmark at 3.52ghz, then run it again at 4ghz, if your average fps goes up, then your cpu was bottlenecking your video cards.

Also running single channel memory hurts performance.
December 27, 2011 4:46:26 PM

Yep it's single channel.. unfortunately 1156 chipsets only allow single channel when running 1600mhz ram. The below link goes directly to the manual for my motherboard.

http://support.asus.com/download/download_item_mkt.aspx...

On page 2-11 it states "Due to Intel Spec definition X.M.P DIMMS and DDR3-1600 are supported for one DIMM per channel only"
December 27, 2011 4:48:34 PM

I did have it at 4ghz but dropped this to 3.52ghz. At 4ghz, on occasion I noticed that there was occasional stuttering... e.g. when playing a driving game the machine slowed for a second or two then came back to normal. at 3.52ghz it doesn't have this effect.

As for the single channel aspect, do you think that using slower RAM e.g. 1333mhz in dual channel will be better? Would this make much difference considering the extra speed on the 1600mhz?
December 27, 2011 5:10:42 PM

spax1981 said:
Yep it's single channel.. unfortunately 1156 chipsets only allow single channel when running 1600mhz ram. The below link goes directly to the manual for my motherboard.

http://support.asus.com/download/download_item_mkt.aspx...

On page 2-11 it states "Due to Intel Spec definition X.M.P DIMMS and DDR3-1600 are supported for one DIMM per channel only"


I think you misunderstood.

That means 1 dimm PER channel. You have 2 channels so you can run 2 dimms in 2 channels for dual channel mode. You CANNOT run 4 dimms in 2 channels is what it means.
December 27, 2011 5:24:40 PM

Well its defiantly not your cards. And I dont think your CPU is underpowered either. Ram seems like best bet. You can have a perfect machine and crap RAM setup, and the game will be slow.
December 27, 2011 5:41:19 PM

Quote:
I think you misunderstood.

That means 1 dimm PER channel. You have 2 channels so you can run 2 dimms in 2 channels for dual channel mode. You CANNOT run 4 dimms in 2 channels is what it means.



Definately confused now!!!!! :-)

I have four RAM slots but only two DIMMS. If I put these in slots B1 and A1 I believe this is dual channel. The machine detects all of the 8gb but windows will say that only 4gb is usable.

If I put the DIMMS in B1 and B2 I believe that this is single channel but all 8gb is usable.

This is as per page 2-10 on the manual. Did I get something wrong?
December 27, 2011 6:14:49 PM

Ok now your confusing me, you never said you had 2x4GB dimms, you stated you had 8GB in single channel which to us means you have 1x8GB dimm.

Oh and I don't have a copy of your manual.....so I cant check page 2-10, lol, but I would suggest you read it to find out which slots your TWO dimms should be in for dual channel configuration.

December 27, 2011 7:02:27 PM

Sorry about that. Yes it's 4gb x 2 @ 1600mhz. I currrently have these in slots B1 and B2. This is in single channel opperation.

For dual channel opperation they should be in B1 and A1. When I do this though it comes detects the RAM however in Windows it only shows as 8gb (4gb usable).

I have tried to downclock the RAM below 1600mhz to see if this allows it to be used in dual channel however I have not had any luck with this. I still get the 8gb (4gb usable)
December 27, 2011 7:39:06 PM

a stick of your ram could have gone bad run a test to see if that is the problem.
December 27, 2011 7:52:28 PM

Hi mistakwa,

These are running fine in single channel mode so the ram is fine. And the manual states the motherboard only runs 1600mhz RAM in single channel mode as per Intel Spec.

The question is more about whether upgrading the CPU, or changing RAM to a lower speed (to allow dual channel) will improve my results. Alternatively, if anyone has a way around this single channel phenomenon it would be great!
December 27, 2011 7:53:30 PM

Would dual channel make much difference anyway? I mean are we likely to be talking 1 - 5 fps difference if anything?
December 27, 2011 8:23:29 PM

1600 mem gets 1600 dual channel - 800MHz per.
-Bruce
December 27, 2011 8:27:50 PM

So it's worth £60 investment in 1333mhz ram as at least it will run at 1333mhz.

Would you imagine that this will make much of an improvement though? I know it's 533mhz... but in reality, when it comes to gaming, will this truely make much difference?

Either that, or does anyone know a way of getting my 1600mhz to work successfully in dual channel?
December 27, 2011 8:33:49 PM

right now you are running at 800 MHz. Putting 1 stick in each channel should work to give you 1600MHz. Maybe try setting the ram setup manually in bios.
-Do you have the latest bios?
December 27, 2011 8:51:39 PM

Thanks Dish-moose, the advice sounds logical. Only problem is that the manual says it will only run in single channel. Do you have any ideas on how to set this up manually? Like is say, I've tried a few settings such as enabling or disabling xmp but what ever i have tried always give 8gb visible and 4gb usable in windows. The only way to get all 8gb usable so far is single channel. Any advice would be great.
December 27, 2011 10:47:27 PM

There's no reason whatsoever your DDR3 will not run in dual channel mode at 1600mhz.
December 28, 2011 7:22:50 AM

morning guys,

Ok, I've tried getting the ram to work in dual channel again and managed to get it working if I up the voltage to 1.65v. I did have to press the mem ok button to start with but hopefully this was a one off.

So... in short I now have 8GB of Ram in Dual Channel mode.

Sadly this made no difference to my gaming speeds and therefore my orginal question.

I've re-run a test on Arkham City and all three GPU's are using 50%. My CPU doesn't seem to be at 100% either though. Is this a CPU bottleneck or something else (AKA bad programming) causing the game not to use all available resource.
December 28, 2011 11:19:31 AM

Just re-done the test with and without crossfire enabled. I get the same FPS basically. So the addition of the 6970 does pretty much nothing. Any ideas?
December 28, 2011 2:25:28 PM

spax1981 said:
morning guys,

Ok, I've tried getting the ram to work in dual channel again and managed to get it working if I up the voltage to 1.65v. I did have to press the mem ok button to start with but hopefully this was a one off.

So... in short I now have 8GB of Ram in Dual Channel mode.

Sadly this made no difference to my gaming speeds and therefore my orginal question.

I've re-run a test on Arkham City and all three GPU's are using 50%. My CPU doesn't seem to be at 100% either though. Is this a CPU bottleneck or something else (AKA bad programming) causing the game not to use all available resource.


So is your memory 1.65v memory??

Some games don't even take advantage of SLI/Xfire, I'm sure many more don't take advantage of tri-fire. So are you trying to tell me that a 6990 is not giving you acceptable playing??

There's no doubt your 2.8ghz cpu is definitely bottlenecking your video cards in tri-fire, but you can't just go by one game, like I said some games can't utilize your configuration.
December 28, 2011 2:38:19 PM

Well it's 1.5 however I saw on some of the manual that other ram was running at 1.6 to 1.65.... thought I'd give that a shot and it works fine. No complains here lol.

As for the CPU bottleneck is there anything I can do to help this?
December 28, 2011 4:03:54 PM

To clarify this a bit more, Battlefield 3, ultra settings at 6256 x 1152... 40 fps. I'm happy with that. But Arkham City, Metro 2033 and Crysis 2 at max settings get around 15 fps.
December 28, 2011 4:10:38 PM

You can run 4 DIMMS at 1600Mhz just fine on most Nehalem/Sandybridge procesors without issue. Just because it is not officially supported does not mean that it will not run
December 28, 2011 4:12:03 PM

Cheers Pinhead. Already got the RAM working in Dual and also got another 8GB on it's way. Not sure if that additional 8GB will make any difference in gaming though.

Question is now how to boost my fps in some games.....
!