Hi all,

I am running Win7 64, 4GB memory, Intel 6850 Quad core.

I just installed a new XFX HD7950, replacing my 5770. It seems to run OK on desktop, browsing the internet, etc.

Whenever I run a game, however, once you get past menus, etc. it hard locks and I have to reboot. In Skyrim, I could run the game, look around, but once I started moving, the screen went black and it hard-locked. I ran Left 4 Dead 2, thinking it was much less taxing and that let me get maybe 2 minutes in and hard-locked.

I have the 4/5/2012 drivers. I'm not sure where to start looking.

In Dxdiag, I notice in the display tab it says "746 MB total memory" and this is a 3GB card - not sure if that's relevant. EDIT: Catalyst Control shows it as 3GB. I have PCI Express 2, it's a PCI Express 3.0-do I need a new motherboard?

Could power be an issue? I have a 750W power supply. It specified to not use split power cables - I have two 6-pin connectors plugged into it, but only one says "PCI Express" - is it possible the other 6-pin connector is not a suitable connector? It's converted from a standard power connector.

I did not load drivers from the XFX disk because it went to a website that made me register and then told me it didn't like my information, so I just loaded the drivers I pre-downloaded from AMD.

Kinda grasping at straws-not sure where to begin!

Thanks in advance

POSSIBLE solution...I disabled the Overdrive (AMD overclocking utility) in CCC and was able to run around Skyrim with no crashes. Only tested for about 5 minutes though...we'll see if it holds.

EDIT: Now it has twice locked up while on the desktop - once after being idle for a couple of minutes and once while I was on a web browser...It chooses a color for the whole screen and requires a restart.

I have watched the CCC temperature meter and it isn't getting hot.

How old is that PSU and what is the Ratings in Amps for 12v Rails, and how many rails is it split into?

Black Screen and hard lock are usually when the GPU Crashes from not getting the power it needs.

My DXDIAG and CCC Both show 3 GB, My system is in My Sig Below.

(edit:04/26/12/1012 EST)(effing auto correct changes my words lol)

^^^ Agreed. Sounds like a PSU problem. Can you get a hold of another 750 to test? I'd look at the PSU as being the culprit first before RMA'ing the card.

A list of AMD recommended PSUs: http://ati.amd.com/certifiedPSU

Thanks guys-I was just thinking along the same lines...I think I need a PSU with two dedicated PCI-E connectors...I have one and the other is 4 pin-connector with a 6-pin adapter. The PCI-E has 6 actual wires in it, so I'm guessing that is not correct. I think that'll be the first thing I try.

My PSU is several years old-no idea of how many rails, etc. I'll have to look up specs for 7950 and make sure I get the correct PSU.

I found other posters online whose memory didn't read correctly in Dxdiag but reads OK in CCC.

The 12v Molex -> PCIe adapters should never be shipped with Graphics cards IMHO,

Your trying to draw 125w during Load from two HDD cables designed to power Two 10w PATA Harddisks,
PSU designers dont put those Connectors on a High AMP Rail if they use multiple 12v Rails. and that causes this problem.


When the GPU is in Desktop mode, the memory changes from 3GB to 128,256,512,768, etc etc
I check my DXDIAG on another screen while playing on the main screen.

Also check PCIe settings in BIOS to make sure its not limiting the BUS, I run on a PCIe2.0 Mobo and I am no where near saturating the PCIe2.0 16 Lane slots bandwidth, even running 3 screens, the max bandwidth i hit is 55%.

Ok, I apologize for being thick, but do you disagree that the first thing to do is get a power supply with two PCI-E 6-pin connectors and then check your other suggestions?

I have a technical background but I have not had to deal with PSU specs other than "Make sure it has a plug that fits your motherboard"

So I'm a little over my head.

yes, get a PSU with dedicated PCIe Power Cables.

OK, thanks for all your help!