How can you NOT get at least 8000 on memory? I've not seen a single report of a card which says that isn't possible.
Core on the other hand changes a lot.
I can get my memory to +625 with no artefacts but the core tops out at 1597. That said it's benched heaven 4 at 1607 or something before so go figure.
My Mem tops out about +625 on stock volts and the core about 1645-1650 on stock volts.
I think most cards are hitting 8000 but not everyone.