Crossfiring 4870 and another GPU?

[Dramamine]

In the upcoming months, I'll be able to get some money that I can spend freely, and I plan on getting another GPU.
I already have a Sapphire HD 4870 Vapor-X, now, I'm wondering what graphics card I can get and crossfire with?

I'm looking at something in the 5700-5800 range, even if that's a bit expensive.
Am I able to crossfire with a 4870 and 5770/5850/5870?

Would going in crossfire be worth it if my other PCI Express 2.0 Slot is at x8 and not x16? Or should I get an x2 graphics card?
4870 x2, etc.

Anyways, thanks for the help in advance.
Also, I haven't been able to find many 4870s for sale, so would using a different brand work? As long as the memory on it is the same?

EDIT: I'm also using a 23" monitor at 1920x1080 resolution, as you can expect, my framerates have dropped a bit in more demanding games. So I think crossfire would help.

 

[sabot00]

Is the 8x PCI-E slot 2.0? If it is 1.1 then no.
You can't CF different series.
You can't get 4870X2's unless from a 2nd-hand site like ebay.
The AIB doesn't matter, any brand works.

 

[Dramamine]

Yes, both slots are 2.0
Sorry I didn't mention.

Also, if I wanted to crossfire, I'd have to get something in the 4800 series?

 

[megamanx00]

You are not able to crossfire a 4870 with a 5770/5850/5870 card. You can only crossfire a 4870 with another 48xx series card such as as the 4830, 4850, 4870, 4890, 4850X2 or 4870X2.

Of course 48xx series cards are in rather short supply so if you are going to crossfire your card act now while you still can.

 

[Dramamine]

Alright, then, thank you, Megamanx00.

Would it be better for me to just buy something like a 5870 or 5850, or should I just crossfire with another 4870?

 

[sabot00]

A 4870 CF will be around the performance of a 5870.
If you can get a refund for the 4870 then sure, but 4870's in CF are no slackers.

 

[Dramamine]

Alright, then, I think I'll try to get a 4870 or 4890, depending on what I can find.
Why in the hell is everything so hard to find?

But I'll try to find something, thanks for the help.

 

[sabot00]

Try to but 2 of the same card if CF, even thought it allows for 4890/4870/4850/4830 the scaling would be far from nice.

If you live in the US:
Cheapest 512 MB 4870
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161268&cm_re=4870-_-14-161-268-_-Product

Cheapest 1024 MB 4870
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161292&cm_re=4870-_-14-161-292-_-Product

Different Cooler, possibly useful for keeping temps down in CF
http://www.newegg.com/Product/Product.aspx?Item=N82E16814129113&cm_re=4870-_-14-129-113-_-Product

 

[Dramamine]

I've looked at those already. :3
If I crossfire, won't I need a GPU with 1 GB of memory?
Or does the memory just have to be equal to or lower?

 

[sabot00]

The memory can be any size, the one with the higher amount would simply lower its RAM to the lower amount.

 

[Dramamine]

Okay, that's good to know.
I had thought that it was only the clocking that scaled down to match the slower one.

You've been really helpful, thanks.