HD 7770 CrossfireX, CPU Bottleneck?


Recently I upgraded my gaming rig to include 2x XFX HD 7770s in CrossfireX mode.  However, I've found that after multiple driver updates, performance is still not what I was expecting.  I'm getting really bad FPS dips in games like Bioshock Infinite, Skyrim, and Crysis 2.  The performance for Skyrim may have even been better on one card.  I'm wondering if my GPUs are being bottlenecked by my Athlon X4 CPU.  When I play games and have OpenHardwareMonitor and MSI Afterburner running, my CPU never quite reaches 100% load, but it does get into the 80s and 90s.  Note that the FPS dip only occurs when my GPU utilization also dips down from the 80s-90s into anywhere from the 70s to 20s.  I get crazy lag spikes and it is really annoying.  However it shouldn't pertain to drivers or software issues, so now I'm asking if it is time to upgrade to a different CPU.  What kind of AMD CPU should I go with that will work well with my AM3+ socket and dual HD 7770s? Thanks so much for any help,




System Specs: 

AMD Athlon II X4 Quad Core Processor

2 XFX HD 7770 GPUs

CM SilentStorm 850W 80 plus bronze PSU

8gb Kingston HyperX ram @ 1333 mHz

MSI 970A-G46 AM3+ Motherboard


additional data HDDs


So after reading through your questions and looking at your current system specs i'm think I can safely say that your CPU is a bottleneck. One of my friends also runs two 7770's but with an FX series quad core and he still has some issues. But since you mentioned that your Athlon is reaching a fairly high load when gaming I imagine you're being limited there.

I would recommend an FX 8350 easily seeing as your system could easily accommodate for it but that depends on what you would want/be willing to spend.

Just out of curiosity, how did you end up with and Athlon X4 in this system? It seems pretty out of place.

Alright I figured as much.  Thanks for the reply!

And I ended up with the Athlon because at the time the system was being built, I was on a budget and that was what I could accommodate.  Things like the boot SSD, the second GPU, and the PSU were added along the line, along with RAM and a 2TB HDD for music creation data storage.  Is there anything else that would work that is similar to the FK 8350? Like a different 6 or 8 core that would actually work well for a lower cost? Of course the 8350 is probably the better option, but I ask because I'm a student on a budget, and won't likely be able to get any money out of old parts. 

You may want to think about changing your RAM to 1600-1866 or overclocking that 1333 RAM to 1600 along side replacing the CPU to a FX-6300.

you'll be just fine with a 6300/6350/8320, i like the 8320 because it's an 8350 that just can't oc nearly as well, but a 6300 will be sufficiant, 6350 is just an overclocked 6300 and is a waste of money

Alright cool.  Thanks guys! I just want to make sure I can play Skyrim and Bioshock Infinite on the high-ultra settings that I should be able to play them on. And Batojiri, I actually have 4gb of 1600 laying around; I meant to order the 1333 as 1600 when I got the additional 8GB but I guess I messed up my order on Newegg.  So I have just been using that :/


This brings to mind an idea, though...could I OC the 1333 mhz to match the 1600 chip that I have?  Because by default, they all run at 1333 mhz when running.  I'd then have 12 gigs of RAM at 1600 mhz...but I'm not sure how that works exactly as far as OCing RAM goes.


I wouldn't recommend it. If all of the DIMMs were 1333 MHz you would be fine but since you are running mixed speed DIMMs things can get unstable if you attempt to overclock 1 DIMM as opposed to the others.

The FX 6300 is probably what you're looking for then. If you can grab the 8320 though, I'd go for that. I also saw your questions regarding your RAM lower in this thread. I wouldn't recommend mixing and matching different DIMM's but I would say take the 8 Gigs you have now and OC those to 1600Mhz when you get your new CPU. 

FX8320 for $145ish on Newegg http://www.newegg.com/Product/Product.aspx?Item=N82E16819113285

FX 6300 for $119 on Newegg http://www.newegg.com/Product/Product.aspx?Item=N82E16819113286

Yeah I tried it last night and couldn't get it up to 1600..I actually went past that but crashed after some gaming; I couldn't get 1600 because of the cpu settings.  Didn't want to change the clock speeds up a bunch. 

Alright thanks.  I've read things about the 8350 melting those g46 boards like the one I have though... Do you think I've have to worry about that if I get a sufficient cooler for the 8320 that I would buy?

(I think I'll opt out of the 6300 because it just isn't as powerful per dollar)

And will this processor make a difference when running things like pro tools, do you think?  Surely having 8 cores should help in that area, although intel is always better for content creation programs, it seems. 

I would just like to add that you mentioned two games where I have had problems with in crossfire with dual 7850's with 1gb vram, there were no underlying problems with the build so I can only assume it was crossfire / driver related

skyrim (dx9)

  • still not fixed, best solution is STILL to switch off the 2nd card (frustrating i know)

bioshock infinite (dx11)

  • should be fixed with the latest drivers, i would get a random stutter every 5 or 6 seconds and then smooth as butter then... random stutter, annoying as f*ck

In my personal experience, the 8350 runs surprisingly cool at stock clocks so I imagine the 8320 would be a little better in terms of heat output. I don't think anything to crazy in terms of the CPU cooler would be necessary. Just go with whatever fits your budget. :)

In Pro Tools specifically, the extra cores will help. The application can easily utilize them. I agree with Intel being better for content creation in most cases but at the price of an 8320, there's nothing available from Intel that can even compete. I still run my Phenom X6 for all of my work with After Effects and it does it pretty good.