How good is SLI and Crossfire?

I have a Radeon HD 7850, and I can run Tomb Raider and Bioshock Infinite at over 60 FPS with the graphics turned all the way up.  How would the graphics and performance improve if I used SLI or Crossfire?  How many cards can I use at once, and would using multiple cards be better than using a card and an APU?

From what I've seen, two 7850s in crossfire will get you about the performance of a 7970 in games that work well with crossfire. You MUST make sure your psu can handle the extra power consumption before you try to run crossfire. Also, make sure your case is well ventilated.

How much better are the graphics using two 7850s or a 7970?  My graphics are already maxed out playing the latest games and they run over 60 frames a second.

Two dedicated GPUs and a processor will crush an APU. But before you consider gual GPU's, there's a few things you need to know.

Make sure your system has dual x16 speed slots (aka 990 chipsets for AMD, and whatever chipset for intel ((i don't deal with intel really))). If you can't run dual cards at x16 speeds, don't bother.

xfire and SLI are a little buggy, and a lot of games don't really like them. In this case, I would really suggest selling your 7850, and taking that money along with the money for the other 7850 and buying ONE really good gpu (670, 680, 7970, 7950, etc) Also, using a single gpu means less power consumption as well as less cables to fuss with.

I don't see why you need to have 2, x16 lanes. If Bobby has PCI-E 3.0 then x8 would equal x16 PCI-E 2.0. If it's PCI-E 2.0 then you're still getting x16 PCI-E 1.0.

I have a z68 motherboard with a GTX 580 and GTX 550 Ti as a dedicated physX card. So my cards are running in x8 mode on PCI-E 2.0 lanes. It really doesn't matter.

If it's 2.0, you want full speed, or you aren't really going to even benefit that much from spending well over a hundred dollars on another card.

In the video, Linus tested this theory and proved that it doesn't really matter.

I only have one PCI-E 3.0 x16.  If I want two cards, I'll have to buy another motherboard with more PCI slots.

you get anywhere between 80-120% performance increase from adding in a second card on well optimized tittles, in my experience


I have dual 7850...

Crysis 3

Single card: few dropped frames and slight stuttering  at 1600 x 900 with everything on v high

Dual card: silky smooth at 1600 x 900 with everything cranked up to max

I would happily sell them both to put the money towards a single 7970 though :D

Crossfire isnt consistant, some games run beautifully and others not so great...

Some even perform worse :s ( you usually have to wait for newer drivers to be released or use stupid hacks).

Just in case your interested..