Help! My machine locks if I overclock my 7900GT by even 5mhz

[JK306]

I'm hoping somebody could give me a few ideas to improve my situation. Heres the story:

I've got a Leadtek 7900GT fitted with a Koolance water block (the one that covers the core and memory(ish)). It never goes above 46C. It was overclocking quite nicely and I had it on 500Mhz core and 700Mhz memory. Had no artifacts or anything so I decided to try 10Mhz more on core and memory and it crashed after one of the CPU tests on 3dmark. The monitors kept flicking on and off like when it changes resolution and the screen was garbled.

So, I reduced back to where I was stable before and it still wouldn't bench. I reset to default and it's completly stable, but if I now try to overclock either core or memory by even 5Mhz the machine will lock up or I'll get an error saying the nvidia driver has crashed.

I've tried reinstalling the driver by doing add/remove programs to get rid of the old one first to no effect.

Any ideas? Could it be a software issue or have I damaged something on the card and should give up while it's still working?

Any advice would be appreciated.

Cheers

 

[pbian]

I have a similar problem, my gpu temp idles at 45C and doesn't go above 55C, but after overclocking to 500/700 my screen scrambles and crashes. Why does that happen when my gpu is clearly cooled properly.

 

[angry_ducky]

I'd try formatting the HDD and reinstalling Windows. Because your PC crashed during the CPU test in 3DMark, that leads me to beleive that your CPU might be overheating. Can you post the rest of your system specs, including case, and power supply?

 

[JK306]

I'm positive it isn't the CPU. The screen got scrambled when (I assume) the graphics card kicked back in after the CPU test and if I take the card to stock speeds I have no issues whatsoever.

My power supply is a Tagan 530W and the graphics card is watercooled by a Koolance Exos system with the nvidia waterblock. Under full load the card never goes above 46C.

Is there anything else I can do to clear any corrupted drivers or anything other than reinstalling windows? I only just got the machine set up how I like it :roll:

 

[FeareX]

reïnstall windows, maybe it helps

 

[pbian]

Ok after doing some research I found out that the problem is in the memory and not the core.

First, I recomend you downclock your memory to 660x2, now try overclocking your core by an insane amount, like from 450 to 550 (well maybe not that much) and try running some tests. ( try reinstalling windows like the other guys said first though ). I have a zalman vga cooler and my gpu doesn't ever go above 50 C, so I know overheating GPU is not your issue since it's water cooled.

Read this:
http://enthusiast.hardocp.com/article.html?art=MTA2OSwxLCxoZW50aHVzaWFzdA

Now let me tell you that the article you just read is wrong... the problem isn't because of BFG or EVGA overclocking but from bad ddr3 memory. Nvidia is just blaming others for their screw ups.

This is a quote I found from a forum post I found:
"From my experience with a BFG Geforce 7900GT OC and eVGA e-Geforce 7900GT Signature Series,

I can confidently say the problem isn't with the graphic core.

The first BFG 7900GT worked absolutely perfect for me. NO errors NO artifacts NO lock-ups. Able to overclock pretty high as 570/1720 WITHOUT any artifacts/lock-ups.

The eVGA 7900GT SS is just a bad card. RMAed 3 times and got 3 bad cards. None of them worked through the 2nd day. And all of them having the same problems, as most of the forum users posted. Downclock the graphic memory frequency solved the problem. Downclock the graphic memory frequency while overclocking core frequency has NO problems AT ALL.

Obviously it's a bad batch of GDDR3 from Samsung OR it's a fundemental PCB design/vreg. components failure.

And more funny thing is, NVIDIA/eVGA NEVER acknowledged this. NVIDIA is saying graphic core is overclocked too much and eVGA is just repeating that they will take care of the customers who need to return the card. NOBODY explained WTH is happening and WHY there are so many users experience the same problems.

I'm already getting a RMA with newegg. I don't like to play with these frequent RMA stuffs. I grabbed a X1900XTX from ebay for the same price as 7900GT SS.

Good luck NVIDIA/eVGA"

I'm gonna RMA my card and see if I get one with good memory modules.
Right now my rig is clocked at 560/660x2 (factory 450/660) and runs without any problems, so I can tell you with 100% certainty it's the ram, I even have zalman heatsinks on the ram.

 

[sailer]

I read about those problems too, which is one of the reasons I decided to buy an ATI card to replace my Nvidia. Somehow, when companies start pointing fingers at each other and both say its the other guys fault, I loose confidence in their product and look for something else.

 

[pbian]

Oh and one more thing, before you run any tests, turn AA all the way up to MAX as it seems like doing this will exponentially increase the frequency of the problem if it does exist so you can detect it faster.

 

[JK306]

Thanks for all the help guys, really appreciate it. I'm going on holiday in a few days so when I get back I'll reinstall windows and have another crack at it.

Interesting about the memory, I had a hunch that might be what it was because of the lack of artifacts and garbled screen.

Cheers

 

[cranbers]

i had problems with 2 different XFX 7900gt cards. I had rma'd and finally on the third one I said to just return them. what I did was run tests, then I had lock ups and weird artifacts while running 3dmark 2001 and 2006. Mainly during the point sprites test on 2001se and it would crash to the desktop during deep freeze on 2006. No amount of messing with the clock helped me at this point. So I returend it.

EVGA has come out with a model number that has been fixed completly of this issue.

The issue is quite simply what you described, overclocking some how damaged the card as a result artifacts, lock ups and weird behavior during 3dmark tests and gaming. But even just leaving the factory they have had issues. The fix being to under clock the card, but even that didn't help me.

I returend the XFX card and replaced it with a EVGA model ko sku with 584 in it . I have had the card for over a week now and have abused it like you wouldn't believe. I replaced the stock cooler with a vf 900 and it's now clocked at 580mhz core and 1.7ghz ram. or 850 as shown in coolbits on nvidia driver.

So yeah, it is one nice chip, when you can get a good card.

It was appearently a memory problem, the old ram is samsung while the new is from infinion. I love this card! Thank you EVGA!

 

[jamesjue]

try another NV driver.