Will Intel Pentium G620 bottleneck ?

maybe no if you are running a 610. maybe yes if you are running a 640. Definitely yes if you are running a 690.

But I know for sure this processor supports DDR3 1066 and PCI express 2.0. The real bottleneck will be there.
 
Go ahead, but remember your RAM's are slow and the PCI slot is old too. You need to upgrade your mobo/CPU/RAM down the line. I would say get the best GPU you can get now and save for future upgrades.

I do hope you have a decent power supply :)
 
just to be in safe side, here are my mobo specifications

CPU
1. Support for Intel ® Core™ i7
processors/Intel ® Core™ i5
processors/ Intel® Core™ i3
processors/Intel ® Pentium®
processors/Intel ® Celeron®
processors
in the LGA1155 package
2. L3 cache varies with CPU
(Some Intel ® Core™ processors
require
a graphic card, please refer "CPU
support List" for more information.)
Chipset 1. Intel ® H61 Express Chipset
Memory
1. 2 x 1.5V DDR3 DIMM sockets
supporting up to 16 GB of system
memory
* Due to Windows 32-bit operating
system limitation, when more than 4
GB of physical memory is installed,
the actual memory size displayed will
be less than 4 GB.
2. Dual channel memory architecture
3. Support for DDR3
2200(OC)/1333/1066/800 MHz
memory modules
4. Support for non-ECC memory
modules
(Please refer "Memory Support List"
for more information.)
Onboard Graphics
Integrated Graphics Processor:
1. 1 x D-Sub port
Audio
1. Realtek ALC887 codec
2. High Definition Audio
3. 2/4/5.1/7.1-channel
* To configure 7.1-channel audio, you
have to use an HD front panel audio
module and enable the multi-channel
audio feature through the audio driver.
LAN 1. 1 x Realtek 8111F chip
(10/100/1000
Mbit)
Expansion Slots
1. 1 x PCI Express x16 slot, running at
x16
(The PCI Express x16 slot conforms to
PCI Express 3.0 standard.)
* PCIE Gen.3 is dependent on CPU and
expansion card compatibility.
2. 1 x PCI Express x1 slot
(The PCI Express x1 slot conforms to
PCI Express 2.0 standard.)
3. 2 x PCI slots
Storage Interface
Chipset:
1. 4 x SATA 3Gb/s connectors
supporting up to 4 SATA 3Gb/s
devices
USB
Chipset:
1. Up to 8 USB 2.0/1.1 ports (4 ports
on
the back panel, 4 ports available
through the internal USB headers)
Internal I/O Connectors
1. 1 x 24-pin ATX main power
connector
2. 1 x 4-pin ATX 12V power connector
3. 4 x SATA 3Gb/s connectors
4. 1 x CPU fan header
5. 1 x system fan header
6. 1 x front panel header
7. 1 x front panel audio header
8. 2 x USB 2.0/1.1 headers
9. 1 x Clear CMOS jumper
Back Panel Connectors
1. 1 x PS/2 keyboard port
2. 1 x PS/2 mouse port
3. 1 x D-Sub port
4. 1 x serial port
5. 1 x parallel port
6. 4 x USB 2.0/1.1 ports
7. 1 x RJ-45 port
8. 3 x audio jacks (Line In/Line Out/
Microphone)
I/O Controller 1. iTE IT8728 chip
H/W Monitoring
1. System voltage detection
2. CPU/System temperature detection
3. CPU/System fan speed detection
4. CPU overheating warning
5. CPU/System fan fail warning
6. CPU/System fan speed control
* Whether the CPU/system fan speed
control function is supported will
depend on the CPU/system cooler you
install.
BIOS
1. 2 x 32 Mbit flash
2. Use of licensed AMI EFI BIOS
3. Support for DualBIOS™
4. PnP 1.0a, DMI 2.0, SM BIOS 2.6,
ACPI
2.0a
Unique Features

Sorry if i'm being an ass
 
just to be in safe side, here are my mobo specifications

CPU
1. Support for Intel ® Core™ i7
processors/Intel ® Core™ i5
processors/ Intel® Core™ i3
processors/Intel ® Pentium®
processors/Intel ® Celeron®
processors
in the LGA1155 package
2. L3 cache varies with CPU
(Some Intel ® Core™ processors
require
a graphic card, please refer "CPU
support List" for more information.)
Chipset 1. Intel ® H61 Express Chipset
Memory
1. 2 x 1.5V DDR3 DIMM sockets
supporting up to 16 GB of system
memory
* Due to Windows 32-bit operating
system limitation, when more than 4
GB of physical memory is installed,
the actual memory size displayed will
be less than 4 GB.
2. Dual channel memory architecture
3. Support for DDR3
2200(OC)/1333/1066/800 MHz
memory modules
4. Support for non-ECC memory
modules
(Please refer "Memory Support List"
for more information.)
Onboard Graphics
Integrated Graphics Processor:
1. 1 x D-Sub port
Audio
1. Realtek ALC887 codec
2. High Definition Audio
3. 2/4/5.1/7.1-channel
* To configure 7.1-channel audio, you
have to use an HD front panel audio
module and enable the multi-channel
audio feature through the audio driver.
LAN 1. 1 x Realtek 8111F chip
(10/100/1000
Mbit)
Expansion Slots
1. 1 x PCI Express x16 slot, running at
x16
(The PCI Express x16 slot conforms to
PCI Express 3.0 standard.)
* PCIE Gen.3 is dependent on CPU and
expansion card compatibility.
2. 1 x PCI Express x1 slot
(The PCI Express x1 slot conforms to
PCI Express 2.0 standard.)
3. 2 x PCI slots
Storage Interface
Chipset:
1. 4 x SATA 3Gb/s connectors
supporting up to 4 SATA 3Gb/s
devices
USB
Chipset:
1. Up to 8 USB 2.0/1.1 ports (4 ports
on
the back panel, 4 ports available
through the internal USB headers)
Internal I/O Connectors
1. 1 x 24-pin ATX main power
connector
2. 1 x 4-pin ATX 12V power connector
3. 4 x SATA 3Gb/s connectors
4. 1 x CPU fan header
5. 1 x system fan header
6. 1 x front panel header
7. 1 x front panel audio header
8. 2 x USB 2.0/1.1 headers
9. 1 x Clear CMOS jumper
Back Panel Connectors
1. 1 x PS/2 keyboard port
2. 1 x PS/2 mouse port
3. 1 x D-Sub port
4. 1 x serial port
5. 1 x parallel port
6. 4 x USB 2.0/1.1 ports
7. 1 x RJ-45 port
8. 3 x audio jacks (Line In/Line Out/
Microphone)
I/O Controller 1. iTE IT8728 chip
H/W Monitoring
1. System voltage detection
2. CPU/System temperature detection
3. CPU/System fan speed detection
4. CPU overheating warning
5. CPU/System fan fail warning
6. CPU/System fan speed control
* Whether the CPU/system fan speed
control function is supported will
depend on the CPU/system cooler you
install.
BIOS
1. 2 x 32 Mbit flash
2. Use of licensed AMI EFI BIOS
3. Support for DualBIOS™
4. PnP 1.0a, DMI 2.0, SM BIOS 2.6,
ACPI
2.0a
Unique Features

Sorry if i'm being an ass