computer case help

will a bigger case help cooling my computer as i got vengean series I want to upgrade Obsidian Series® 750D Full Tower ATX Case or Obsidian Series® 900D Super Tower Case and I want only simple water cooling cpu and gpu only?



is there big differences from Obsidian Series® 750D Full Tower ATX from Obsidian Series® 900D Super Tower Case?



are they silent and more cool from all extra space?



fratal design r5 are this one good for water cooling?



Operating System

Windows 8.1 64-bit

CPU

Intel Core i7 4790K @ 4.00GHz 47 °C

Haswell 22nm Technology

RAM

16.0GB Dual-Channel DDR3 @ 899MHz (9-10-9-27)

Motherboard

ASUSTeK COMPUTER INC. MAXIMUS VI HERO (SOCKET 1150) 28 °C

Graphics

G236HL (1920x1080@60Hz)

NVIDIA GeForce GTX 970 (MSI) 38 °C

Storage

931GB Western Digital WDC WD1003FZEX-00MK2A0 (SATA) 35 °C

232GB Samsung SSD 840 EVO 250GB (SSD) 35 °C

Optical Drives

HL-DT-ST DVDRAM GH24NSB0

Audio

Realtek High Definition Audio