failing to overclock core/shader clock (lines) GeForce 9800 GT

hello everyone, asking if maybe it is possible to do something with the problem i have, sorry for bad english > <, my PC and all it's parts are 7 years old and well somehow it still alive, and because time goes on, i decided to start overclocking it, just a little bit at least.. , got no problems with overclocking MHz from 2.7 to 2.94, but something strange happening when trying to overclock Core Clock or Shader Clock in EVGA Precision , in all the games, all the gfx/graphic starting to jumping from one direction to another, looks like jumping lines for me, FPS going higher but it is impossible to play like that, at the deffault everything is normal, if i set it lower then it's still normal, but if i set it slightly higher then this thing starting to happen and well because i am a novice in this thing , have no idea how to fix it, i did tried older versions of the graphic drivers, but sadly it still were the same, asking if it's still possible to boost the shader and core clock but without red lines? in bios for example, or it is just better to not touch these 2 and stick with memory clock? because it's the only one with which i have no problems when i change it from these 3 in EVGA Precision , p.s. remember that i have this PC for 7 years so it's normal that i did started attempts to to overclock it because oh my god it's still alive .. xD, here is a video of what happens when i boost a little the shader and core clock YouTube

and here are some of my information about processor and what it have, not sure if i missed something or did not, as i said i am quite novice, but tried to mention as much as possible,
even if your replies guys will not help me or i will be unable to made some(or even every) of the options because being unskilled, they might help some other people who got the same problem, hope it will , anyways thanks to everyone who will try to help ^^


Field Value
CPU Properties
CPU Type DualCore AMD Athlon II X2 4400e
CPU Alias Regor
CPU Stepping DA-C2
Engineering Sample No
CPUID CPU Name AMD Athlon(tm) II X2 4400e Processor
CPUID Revision 00100F62h
CPU VID 1.3500 V
North Bridge VID 1.1750 V

CPU Speed
CPU Clock 2943.0 MHz (original: 2700 MHz, overclock: 9%)
CPU Multiplier 13.5x
CPU FSB 218.0 MHz (original: 200 MHz, overclock: 9%)
HyperTransport Clock 2180.0 MHz
North Bridge Clock 2180.0 MHz
Memory Bus 436.0 MHz
DRAM:FSB Ratio 12:6

CPU Cache
L1 Code Cache 64 KB per core
L1 Data Cache 64 KB per core
L2 Cache 1 MB per core (On-Die, ECC, Full-Speed)

Motherboard Properties
Motherboard ID 06/22/2009-RS785-SB710-7A66BG05C-00
Motherboard Name Gigabyte GA-MA785GM-US2H (2 PCI, 1 PCI-E x1, 1 PCI-E x16, 4 DDR2 DIMM, Audio, Video, Gigabit LAN, IEEE-1394)

Chipset Properties
Motherboard Chipset AMD 785G, AMD K10
Memory Timings 5-6-6-18 (CL-RCD-RP-RAS)
Command Rate (CR) 2T
DIMM1: Micron 16HTF25664AY-800G1 2 GB DDR2-800 DDR2 SDRAM (6-6-6-18 @ 400 MHz) (5-5-5-15 @ 333 MHz) (4-4-4-12 @ 266 MHz)
DIMM2: A-Data DQPE1A16 1 GB DDR2-667 DDR2 SDRAM (5-5-5-15 @ 333 MHz) (4-4-4-12 @ 266 MHz) (3-3-3-9 @ 200 MHz)

BIOS Properties
System BIOS Date 06/22/09
Video BIOS Date 05/31/09
Award BIOS Type Award Modular BIOS v6.00PG
Award BIOS Message GA-MA785GM-US2H F2
DMI BIOS Version F2

Graphics Processor Properties
Video Adapter Gigabyte GeForce 9800 GT
GPU Code Name G92GT (PCI Express 2.0 x16 10DE / 0614, Rev A2)
GPU Clock (Geometric Domain) 301 MHz (original: 740 MHz)
GPU Clock (Shader Domain) 602 MHz (original: 1850 MHz)
Memory Clock 100 MHz (original: 900 MHz)

Hardware Description NVIDIA GeForce 9800 GT
Hardware Driver nvd3dum.dll (9.18.13.4144 - nVIDIA ForceWare 341.44)

Direct3D Device Properties
Total / Free Video Memory 512 MB / 411 MB
Rendering Bit Depths 8, 16, 32
Z-Buffer Bit Depths 16, 24, 32
Multisample Anti-Aliasing Modes MSAA 2x, MSAA 4x, MSAA 8x, CSAA 8x, CSAA 8xQ, CSAA 16x, CSAA 16xQ
Min Texture Size 1 x 1
Max Texture Size 8192 x 8192
Unified Shader Version 4.0
DirectX Hardware Support DirectX v10.0