Can I run Nvidia GTX 660?

[Cronsky]

My computer is a HP pavilion. And I already know that I need a new power supply. The main thing I'm worried about is if it can fit and If I have enough fans to support it. I have one fan that isn't attached to anything specific, two total, not including the graphics card of course. The GTX660 has two fans, my current one has one really small one. My ATI radeon HD 5450 averages in the 50c degrees. My friend said as long as I have a one pci express x16 slot. But the GTX660 requires "one PCI express x16 slot 3.0" I am confused, since it is 3.0 can I NOT run in it this one? I don't have any number after it, so it's just standard. I am getting an overclocked one which gives me fear that my computer will just fry out. My friend said that adding more fans is a hard and/or expensive task depending if you get someone to do it for you. I was thinking about water cooling but I have no idea how to install it or if it'll fit. Some advice on all of these things mentioned is GREATLY appreciated.

Thanks,

Link to the page showing my motherboard
Motherboard Specifications, MS-7613 (Iona-GL8E) HP Pavilion p6345a Desktop PC | HP® Support

Motherboard specs:

Form factor
-Micro-ATX: 24.4 cm (9.6 in) x 24.4 cm (9.6 in)

Chipset
-Intel H57 Express

Front side bus speed
-2.5 GT/s

Memory upgrade information (doubt it's important)
-Supports DDR3 DIMMs only
-Dual channel memory architecture
-Four DDR3 DIMM (240-pin) sockets
DIMM types:
-PC3-10600 (DDR3-1333)
-PC3-8500 (DDR3-1066)
-Non-ECC memory only, unbuffered
-Supports up to 16 GB on 64-bit PCs
-Maximum memory only if using 4GB DDR3 DIMM modules.

Video
-Integrated Intel H57

Expansion slots
-One PCI Express x16 slot (for graphics card support)
-Three PCI Express x1 slots (for cards such as network, sound, or tv-tuner)
-One PCI Express x1 minicard socket

Internal connectors
-One CPU fan connector
-Four DIMM sockets
-One 24-pin ATX power connector
-One 4-pin ATX power connector
-Four SATA connectors
-Six USB headers, supporting 8 USB connections
-WLAN card LED connector
-Clear CMOS jumper
-Clear BIOS password jumper
-Front panel connector
-SPDIF out connector
-ROM Recovery
-1394 connector
-Speaker
-Front panel audio connector
-One PCI-E x16 connector
-Three PCI-E x1 connectors
-One PCI-E Mini-Card connector
-One PC fan connector

 

[Cronsky]

I had the same computer and If I remember correctly I could JUST fit it in but there wasn't enough airflow to support it and it was very hot. It runs fine on the motherboard and cpu but of course like you said you need a new power supply.. which may be difficult to put in since it is a company case..

 

[jessterman21]

Upgrade that PSU to at least 400w. Get a short 660 with a good cooler (like the MSI TwinFrozr) and you should be okay. PCIe x16 1.0, 1.1, 2.0, 3.0 slots are almost all compatible with all graphics cards.