Lately I've bought the following components and finally built it (HTPC/Gaming PC purpose):
CPU Intel Core i5-2400S 2.50GHz (65W, 6MB Cache, DDR3-1333 memory limit)
CPU Cooler Scythe Big Shuriken Low Profile CPU Cooler SCBSK-1000
MOB P8H67-M EVO
GPU Sapphire ATI Radeon HD 5670 Ultimate Passive
SSD OCZ VERTEX 30GB
HDD SAMSUNG Spinpoint F3 HD103SJ 1TB 7200 RPM 32MB Cache SATA x 2
PSU Enermax Modu87+ 500W
Case Silverstone Grandia GD05 (3x120mm fans)
Memory G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 DDR3 1333 CL8 (F3-10666CL8D-4GBRM)
DVD ASUS DRW-24B1ST
Mouse/Keyboard Logitech Dinovo Edge
My problem is that when I tried to insert the above passive GPU, the case height wouldn't allow it (there are ~2cm extra) so I need your advice on a similar performance card which would allow Dolby TrueHD & DTS-HD Master Audio bitstream and all the newest format that any ATI HD5XXX allow, would be passive and would fit in height to my Silverstone GD05 case (The current dimensions of the card are (H)15.5cm x , (D)3.6cm, (W)19.8cm and as mentioned, the height shouldn't be more than 13cm).
As for playing performance I'm mostly playing Battlefield II, Fifa2011, Crysis, ...
I can't see any passively cooled cards at the level your current card is in. The reason your current card can't fit is due to the elaborate passive heatsink that is on the top of the card, thus blocking any chance of the case closing.
You will be able to get normal sized cards with fans but passively cooled cards without a silly sized heatsink from ATI are the 5450 range, which aren't meant for gaming at all.
To get anything near decent gaming performance, you're going to need at least a 5770 at 1080, at 768 (720p) you'll be able to get away with a 5670 (actively cooled).