How would I know if my GPU is crashing/ making Invalid shares?

[twist3d1080]

I'm really new to BitCoin, and although this is very exciting possiblity, I am worried that might my GPU overclocked to much. I'm using GUIminer to mine at a rate of 233mh/s on a Radeon HD 6850.  If my GPU is being pushed to far would it report an error to the GUIminer log?  Would the program just crash?  While pooling through Deepbit My gpu utilization is going up and down.  My fan is ramping up and down to accommodate the temp variations due to GPU utilization (very annoying).  In my console I've noticed that its giving a error connecting to bitcoin RPC.  Then it seems fine and then it errors again, is that due to a crashy gpu or is that because Deepbit's servers are still underattack?  Anyways I'm sorry if this question has been asked a million times.  I tried to use my google-fu with no avail. Thanks again for your help.

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[lessPlastic]

If you've overclocked your card to the point of instability, you'd have freezes, glitches on your screen, etc.

Try using ATITool to check stability, or look at the list of mining hardware (google it) and find your 6850, see what other people's overclock settings are.

[twist3d1080]

Thanks for the help, I guess it was just due to network instability.  I've changed pools and had no problems since.