I7-870 to FX-8350 worth upgrading to?

If gaming is your requirement then its not really worth upgrading that CPU to any CPU as the gains will only be slight or marginal. If you want to keep your setup consider upgrading your Graphics solution and/or adding a SSD is a fine little upgrade.

In general computing the FX 8350 will be a upgrade but I don't know if its exactly cost efficient at $200ish its still a higher price to pay.

No, it's not worth it. Sarinaide is right. Spend any extra money on either a better graphics card, an SSD, or more RAM.

And if you do wish to upgrade to a new processor and motherboard.

Just upgrade to the i5 3570k. Can get them for avout $169 now at Microcenter.

The i7 is a very fast processor. Was one of the best in its day. The only meaningful upgrade is going to be to a Sandy or Ivy bridge I7 which means $300 processor and a new motherboard.

Vs the FX8350 it it pretty much even. Loses a few and wins a few:
http://www.anandtech.com/bench/Product/697?vs=107

You still have a great CPU. What's it not doing for you? Is there a problem or just upgrade-itis?

Asus M5A99FX PRO R2.0 AM3+ 990FX - AMD Phenom II X4 965 Black Edition Deneb: $237

That will get you started on your road to recovery.

current specs?

Uhh, really? You are recommending i7 to Phenom X4?

I recommend keeping your cpu for atleast another year. It's not really letting you down is it? If so, have you tried overclocking it? If you've got the upgrade bug bad, how about building a cheap htpc or spare computer to tinker around with?

@Twelve

Well, the 965 BE is only 25% worse than the 2500k. Costs 50% less, too.
Also, with that motherboard, he could overclock the 965 to pretty high speeds, which will make the 965 as good as an i5 2500k @ stock.

His existing processor is already nearly as fast as a 2500k, so he's going to be spending $225 to get slightly worse performance. Great "upgrade"!

Why do you need a cpu upgrade?