Gpu location and type

hello.
my pc contains:
Processor: Intel(R) Core(TM) i3 CPU 530@ 2.93GHz, with passive ninja 2 rev.b cooling on it.
Card name: Intel(R) HD Graphics
System Model: H55M-USB3
haupauge tv card
Memory: 4096MB RAM
Samsung 1 TB h-drive
enermax eco 80+ 500 w active power supply .
Antec p182 case.


I'm planning to upgrade my gpu.
since I'm a silence frick , and build according to that this pc, i want very much to use passive cooling gpu.

our use with graphics/games is moderate, but i would like to buy a gpu that will aloud us expansion options in this area in the future.
the candidates for my new gpu are:
gtx 650 (the regular, not the high power ti),
or the hd 7770.

the fan on the ninja cooling is now working, i still have to check about it, since i remember that I've been told that it starts working only when the temp. rising, and my current temp. are relay low (18-27 c). maybe i have to control it somehow.

my first question is if it'll be safe to use a passive gpu on this gear ?
i heard an opinion that the p182 is not one of the ventilated cases ( but i know that it has a lot of room inside) so it can be risky with 2 of those elements as passive (as i said still have to check about the ninja). currently i use the case fans on lowest speed, and after checking higher speeds noise, the only speed i 'can live' with is the lowest one.

another issue that bother's me is the ninja heat sink take a lot of space, and the pciex. x16 slot is the upper one ( gigabyte h55 usb3 board), very close to the cpu/ninja , so even that I'll can locate the gpu on the x16 slot, I'm afraid that there will not be sufficient ventilation between the two, and they will heating each other.
my other option is to use the x4 slot, which us the lowest one. (if that will be the case can someone estimate the loss of speed by doing it?).

the next issue is , as far as i know, there is no passive version for the gtx 650.
the hd 7770 has passive version:http://www.tomshardware.com/news/sapphire-radeon-gpu-77...
but they don't sell it in my country and i didn't found it even in the net.

can someone try to guide me with those subjects ?