6800gt - Memory error

When I plug my 6800gt into the PCI-E port the motherboard gives me a memory related error message. Odd thing is sometimes it will work for a bit but when I turn off the machine and then turn it back on again the memory error will return.

I have tried pretty much everything and I can't nail it down. The card used to work fine when I got it originally but it seems to be all but knackered at the moment.

Any ideas people? Currently using a crappy 8mb Matrox PCI card to keep me ticking over :shocked2:

Could be just knackered, how old is it?