What is "write combining"?

[MrChupon]

First, a little background. I'm having the (infamous?) Nv4_disp.dll infinite loop issue in Windows XP Pro.

I did not come here to plead for help with it, as I see there are a million other threads in the archives discussing the issue.
That said, if there really is a be all and end all fix, I wouldn't mind if somone piped up...

Anyhow, one of the many pages I've read on how to solve this issue suggest that I go into display>settings>advanced>troublshoot and uncheck "enable write combining". Windows XP does have a little pop up box that tries to describe it, but it doesn't really let you know what it is really used for.

So i turn to you, the famed anandtech public!

Does anyone know what exactly this option would disable? Would it be relatively minor things? What kind of performance hit am I taking by disabling this feature?
I hope its nothing too major.. I didn't buy a Ti4600 so I could disable all the feature it provides.

Also, in the same window, there is a "hardware acceleration" slider. How badly are you disabling your system by messing with the hardware acceleration? Can that functionality be replaced through software acceleration, provided I have enough speed and RAM to make up for the extra load?

Thanks for any and all help,
Rob

 

[MrChupon]

bump in case anyone knows.

 

[splice]

Write Combining is a memory burst transfer technique. Writing small bytes (8,16,32 edit: bits pixel data) of data to memory is very inefficent. So WC caches these writes to minimize memory access. Cache here mean non-snooped buffering. It will buffer-up, say, 64 bytes and burst them out to memory when the buffer is full. Also, writes to the same memory address will get clobbered by newer writes. Say if you write data five times to the same memory address, only the last one will actually get written out.

 

[BFG10K]

Write combining groups up small data chunks into larger, burstable transactions.

 

[TNTrulez]

What does this infinite loop bug do?

 

[John]

Originally posted by: TNTrulez
What does this infinite loop bug do?

It gives you a BSOD. You need to try different detonators if you are the recipient of the evil deed.