Is My GPU Strong Enough for Tri-Monitor Gaming??

[hoco_xxsamxx]

Hello, I am saving up to buy three monitors so I can play games in 5760 x 1080 resolution. I just bought the second monitor and tried to play a game in 3840 x 1080, and I had some frame lag. This concerned me because my GPU, ASUS HD7850, can usually run any game on max settings at 60 fps.

When I get my third monitor, how will the performance be?
Should I buy a second ASUS HD7850, and run them in crossfire?
Or should I just buy a new, more powerful card?

Thanks!

~Sam

System:

Spoiler

OS Name Microsoft Windows 8
Version 6.2.9200 Build 9200

Processor Intel(R) Core(TM) i5-3570K CPU @ 3.40GHz, 3401 Mhz, 4 Core(s), 4 Logical Processor(s)

Installed Physical Memory (RAM) 16.0 GB
Total Physical Memory 16.0 GB
Available Physical Memory 12.1 GB
Total Virtual Memory 32.0 GB
Available Virtual Memory 20.9 GB

[Display]
Name AMD Radeon HD 7800 Series
PNP Device ID PCI\VEN_1002&DEV_6819&SUBSYS_042C1043&REV_00\4&BAB4994&0&0008
Adapter Type AMD Radeon Graphics Processor (0x6819), Advanced Micro Devices, Inc. compatible
Adapter Description AMD Radeon HD 7800 Series
Adapter RAM (2,147,483,648) bytes
Installed Drivers aticfx64.dll,aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
Driver Version 12.104.0.0
Resolution 1920 x 1080 x 60 hertz

 

[hoco_xxsamxx]

Bump, please try to answer.