HP Proliant ML350 G6 Dispaly resolution problem in RHEL 7.2

[SrikanthISRO]

Dear all,

I ahve been using the HP Proliant ML350 G6 server for some time with RHEL 6.5 . It has got ATI ES 1000 onboard graphics controller. With RHEL 6.5, I was able to get better resolution (around 2K may be). Recently I have installed RHEL 7.2 in this server. But now the display resoultion has come down to 1024x768 (best case) and one more option(800x600) only available to select from. I have tried to add the resolultion manually by the command 

> xrandr --addmode default "1680x1050_60.00" but it has come out with message 

> xrandr: Failed to get size of gamma for output default.

Can any body suggest me the soultion for the above error or can guide to buy a new graphcics card whcih is compatible to this server.