Warning: ARK is not much safe either, I saw on reddit some days ago some guy complaining that he bought a I3 after checking it on ARK, and after the purchase, Intel disabled the feature on all i3 and changed ARK too, silently. (It was related to some feature Intel also tried to implement in the 2 previous generations but seemly is buggy)
EDIT: I hit the post limit... Yes, I do think it was TSX
Also some Skylake i5s and i7s had TSX issues, but I don't know whether Intel managed to fix them or is going to disable TSX. So far ARK lists them as supported.
I wouldn't expect anything different, but saying that disabling a feature that was advertised and paid for it's a good thing is plain weird. A good thing would be a recall or reimbursement.
When it works, you get support for database-like transactions on RAM (only small transactions, it isn't black magic).
When it fails, you get all kinds of random crashes at random times.
Introduced in Haswell, turned out to be buggy and Intel famously disabled it with ucode update. Since then, they quietly disabled it also for several Broadwells and Skylakes which didn't fare much better than Haswell.
edit: it seems I misread parent's post as "what is TSX"
http://ark.intel.com/products/36547/Intel-Core2-Quad-Process...