HD 7870 Compatible with current setup?

So my current specs are as follows:

MB: MSI P55 - GD65
CPU: Intel i7 860 OC'd to 3.8
GPU: 1GB HD 5850
PSU: 650w Corsair HX series
RAM: 4GB (2x2GB) DDR3 1600 MHz
Plus a 128GB SSD and 1TB HDD

My setup is nearing 4 years old and I'm looking to upgrade a couple things, the RAM to 8GB, and the graphics card. I was hoping someone could help me out by letting me know whether my PSU will be OK powering a HD 7870 and if it'll be OK with my mainboard, plus anything else that might be helpful, whether a 7870 is a big enough upgrade to my 5850, or if there are any better alternatives for around the same price, etc.

Thanks in advance.

Your PSU will easily power a 7870 or a 7950 if you desire. the 7870 is a good upgrade from the 5850 and will notice the difference, especially with more ram on the card, 4gb to 8gb is also a good upgrade.

Make sure you're using a 64 bit o/s (XP Win7, Win 8) or you won't see any difference from the extra 4GB.

If I was you I'd be tempted by the 7950 with the offers they got on at the mo and free games.

Butuz

Yea it is, OS is Win 7 64bit.

have a look at the 670s that are at 161 atm/ Scan and OCUK are selling them.

Your power supply is fine and I would look at 670's or 7950's if I were you personally, if you can afford a bit more.
To see if you think its worth while look at benchmarks for the games you want to play. Although if its AMD try and find ones using the latest drivers.

Your PSU will be fine. What is your budget??

Around £150-£180, I've seen plenty of 7870s and a couple 7950s in that range, but I might give it a few months if there's a chance of a price drop before the end of the year.

EDIT: I should say that the 670s I've looked at are slightly above that, but like I said, if there's a chance of a price drop before the end of the year I don't mind waiting a few months if they're out performing the 7950.

I'm late to the party, but I agree with most of the guys here. Your mobo will allow for the 7000 series, and the PSU will power them fine and will notice a better/greater overall performance in gaming when going to 8GB. As for your hard drives - good as is :)