Using my new 7990

sof006 · 28 Oct 2013 at 01:17

Hey just trying out my new 7990 and need some expert advice.

I am using a MSI 990XA-GD55 and using the 7990 in the PCIe X16 slot and seem to be having some issues, my FPS in certain games (mostly Crysis 3 and Farcry 3) seem to dip a lot. My crossfire appears to be working just fine however according to MSI Afterburner my 2nd GPU is running at full 99% load and the first GPU is running at around 60/70% load... So I checked GPU-Z and it says my send GPU is running at x4 and the first is running at x16. What is going on? I am rather confused...

The rest of my specs are - FX 8150 running at 4.2GHz and using 16GBs of RAM running at 1333MHz, as well as a lovely XFX 750W 80 Plus Gold PSU. I have checked temps and everything is running fine, nothing is overheating.

Looking for some help! Thanks!

8 Pack · 28 Oct 2013 at 15:52

Both GPU should be running at x16 PCI X 2.0. To check this you will have to run a graphical programe such as a bench or a game as in the desktop the Drivers scale down the GPU to save power.

As of your stuttering in games this could be several issues. What Res are you playing at because even a 7990 cant handle those games at full settings at mega resolutions. Your CPU also could be bottle necking in the most intense parts of the game.

I would first update drivers and then monitor CPU and GPU use while playing and see if maybe CPU is a bottle neck.

sof006 · 28 Oct 2013 at 16:50

8 Pack said:
Both GPU should be running at x16 PCI X 2.0. To check this you will have to run a graphical programe such as a bench or a game as in the desktop the Drivers scale down the GPU to save power.

As of your stuttering in games this could be several issues. What Res are you playing at because even a 7990 cant handle those games at full settings at mega resolutions. Your CPU also could be bottle necking in the most intense parts of the game.

I would first update drivers and then monitor CPU and GPU use while playing and see if maybe CPU is a bottle neck.

Okay I will do that. The res I am running at is 1920x1080, I plan on adding more monitors in the future (hence why I bought the card). I have the CPU clocked to 4.2GHz to see if that improves anything. I'll post back with my update soon

grouch4568 · 28 Oct 2013 at 17:58

I've been trying to help sof006 work this out but I've no experience with dual GPUs.

Just for my own benefit, why would the 2nd GPU's bus interface show as PCI-E 3.0x16 @ x4 3.0? Is that GPU specific and dictating what the motherboard runs it at? With a PLX chip on the GPU, it should be x16 too shouldn't it?

Originally, I figured it was bottlenecked by the CPU but that bus interface is nagging me I might be wrong.

8 Pack · 28 Oct 2013 at 18:40

It would not be the interface. Yeah running off PLX shoudl be 16x. When you load 3D is it the same???

sof006 · 28 Oct 2013 at 19:11

8 Pack said:
It would not be the interface. Yeah running off PLX shoudl be 16x. When you load 3D is it the same???

Yeah when I load 3D games it stays at 4x :/ also it says PCIe 3.0 when my motherboard quite clearly isn't capable of 3.0.

grouch4568 · 28 Oct 2013 at 20:01

Hope you don't mind me chipping in here as well, sof006, but I figured any more details I could supply might help solve this. It's bugging me as well now.

I asked him to do a 3D11 run, 8Pack, and this is the result:

http://www.3dmark.com/3dm11/7380337

It looked about right to me considering it's a 7990 paired with a 3.6ghz (at the time) 8150 and 1333 ram.

The only things left I can think of is trying it in the bottom x16 slot to see if the bus increases. I've read from time to time the slot (or GPU pins) can get dirty and a clean can change the bus speed readout or the motherboard itself isn't reporting the right value.

I'll chime out again now and leave you with the expert sof006.

Keep the breaking those records 8Pack.

almighty15 · 28 Oct 2013 at 20:03

It's your CPU..... A 7990 needs a lot of CPU grunt to max it out and keep it fed with data.

sof006 · 28 Oct 2013 at 20:42

almighty15 said:
It's your CPU..... A 7990 needs a lot of CPU grunt to max it out and keep it fed with data.

I understand my CPU might not be powerful enough to supply full FPS but it still doesn't explain why its running at PCIe 3.0 when my board is clearly not even capable of 3.0... :S

8 Pack · 28 Oct 2013 at 22:31

I dont have that MSI board in my lab but I could mock up something similar tomorrow I think and report back.

sof006 · 28 Oct 2013 at 23:55

8 Pack said:
I dont have that MSI board in my lab but I could mock up something similar tomorrow I think and report back.

Great! I hope to hear from you soon, it would be great to figure out what is giving me such strange readings. Thanks for your help

grouch4568 · 1 Nov 2013 at 11:34

A PCI Express® 3.0 PLX bridge to connect the dual ASICs in an internal AMD CrossFire™ technology configuration.2 This interconnect provides 48 lanes (96GB/s) of bandwidth.

http://community.amd.com/community/...n-hd-7990-is-the-worlds-fastest-graphics-card

That would explain why GPUZ was reading PCIE V3 on a motherboard with V2 wouldn't it?

I still can't work out why it says the 2nd GPU die is PCI-E 3.0x16 @x4 3.0 though. Unless it was a bad reading in GPUZ. I can't get in touch with him to try a different version.

I hate it when I can't work something out.