Video memory error not reported when 3D graphics cycle is check on

[Elie]

Could someone help me understand this issue. I am using BurnInTest V5.1 Pro to test my system. The system is:

Biostar M7NCD Ultra V 1.0 motherboard
AMD Athlon XP 3000+
512 MB PC 2700 DDR 333 (configured 256 x 2 Dual channel)
ATI Radeon AGP 64 MB DDR 4X (the 8 X has been disabled in motherboard Bios)

Here is the situation: When I run BurnInTest Pro I get a "Video memory corruption". I removed the card and installed an identical card from my son's computer and ran the BurnITest and the system passed with no error. These results are consistently reproducable with each of the cards. So okay I figured my video card is shot. Then messing around with the BurnInTest configuration and my defective card I got the following results consistently; the card passes the test when the 3D graphics is checked in BurnInTest to be tested. This is the only time that the Video card passes.
The video card fails with a "Video memory corruption" error each time the 3D test in not selected regardless whether I checked the Local video memory only option in the BurnInTest configuration menu or that the All video memory has been selected. And the opposite is true; the video test will pass regardless which video memory option has been checked as long as the 3D test has been activated. All the other tests such CPU, memory (RAM) etc pass regardless. The 2D graphics test has been selected in all the tests of course.

Could someone please help me understand why would this happen? How come memory video memory is reported corrupt only when the 3D graphics test is not selected.

Thanks all.

[David (PassMark)]

There is an old post about Video Memory Corruption, in general a couple of these errors are nothing too serious.

If you activate the 3D test, then the 3D test will use some of the video RAM for its textures (textures are just image files wrapped around 3D wire frame objects). Becuase the 3D test grabs some of the video memory, there is less free video RAM available for the 2D test to exercise.

Some video RAM is also used for the normal desktop display.

So the 2D test is never able to test all of the physical video RAM. But without the 3D test runnning, more RAM can be tested.

[Elie]

I see that not all the memory can be tested. But on the 2D graphics it found the corruption every time when the 3D graphics test was not selected to be ran. And every time I had both the 2D and the 3D graphics tests selected to run, no errors were found. And if I am understanding you correctly, the bad memory may have been grabbed by the 3D graphics test routine. In this case shouldn't the 3D graphics test report a video memory corruption? Is it possible that when the 2D and the 3D are both selected then the bad memory area is somehow not tested? Could it be that the bad memory is being grabbed by the program to open the additional 3D test window and therefore not getting tested?

I will try selecting both 2D and 3D tests and deselect one test and see if that will make the bad memory available for testing. I shall report back the results.

I ran the 2D graphics test without the 3D test a couple of times. One time I selected lines and bit maps and the second time around I selected EMC and the system passed both times. But I get the error only when video memory being tested and without the 3D test.

Thanks for the help.

[David (PassMark)]

...the bad memory may have been grabbed by the 3D graphics test routine.

This is a distinct possibility yes.

Or you could be seeing the issue detailed in the old post about Video Memory Corruption. And for some (unknown) reason the cache issue is not provoked when the 3D test is also running.

...shouldn't the 3D graphics test report a video memory corruption?

The 3D test doesn't verify the RAM contents. It was designed to exercise the 3D acceleration hardware on the video card. But really bad memory corruption would result in a corrupted 3D image (wrong colours, flashing textures, missing or malformed 3D objects, crashes, etc..).

[Elie]

Thank you very much Mr. PassMark. The system didn't crash during any of the tests. I disabled the disks test hoping that may free up some corrupt memory and ran both 2D and 3D tests simultaneously and no errors reported and no crashes. I will look at the link you posted. Thanks again.