Need some computer wizards help

[Kryptic Gaming]

Alright so ive been gaming for a little over 6 months now, i mostly play Rust, CSGO, some some Minecraft. CSGO and Minecraft run perfectly fine, but in Rust my frames drop really bad. Im not sure if this has anything to do with whats casuing the FPS drops, but when i open my task manager it says 99% or 98% physical memory, so i was thinking that might be an issue, but then again i have no clue. Here are my specs

Specs:
Windows 7 Professional 64-bit SP1
CPU
Intel Pentium G3258 @ 3.20GHz
Haswell 22nm Technology
RAM
8.00GB Dual-Channel DDR3 @ 666MHz (9-9-9-24)
Motherboard
Gigabyte Technology Co. Ltd. H97M-D3H (SOCKET 0)
Graphics
DELL D2015H (1920x1080@60Hz)
2047MB NVIDIA GeForce GTX 750 Ti (ZOTAC International)
Storage
298GB Western Digital WDC WD3200AAJS-60Z0A0 ATA Device (SATA)

Keep in mind i will be upgrading my motherboard and cpu.

New Motherboard and CPU:
i5 2500k
MSI Intel H61 LGA 1155 DDR3 USB 2.0 Micro ATX Motherboard

What is the most important thing i should upgrade next?

 

[toshibitsu]

If you're going to stick with 1155, I'd invest in either an i7-2600k or an i7-3770k. 8GB of memory is decent. Although the video card... I'd replace that with a 1050 Ti(or if you can afford it, a 1060).

 

[boosted1g]

Is the game using most of your memory or something else?

What is CPU percentage. I would imagine a g3258 will not fare well in RUST and other games that want a well threaded CPU instead of a measly dual core

 

[Sam Poland]

You're going to have to upgrade that video card no matter what, might as well make it #1 on the list.

The small amount of RAM on your existing video card could be responsible for the FPS drops and also what is eating up your system RAM:
http://www.tomshardware.com/forum/365827-33-what-vram

 

[TMTOWTSAC]

Rust recommends as its min/max requirements C2D E4400 - i5 4430 and gtx 650 - 980. Your G3528 is probably a lot closer to the i5 4430 than the the 750 ti is to the gtx 980, so I'd probably upgrade the GPU first. And if you decide to jump sockets it can carry over into the new build.

Despite being an H97 board that specific Gigabyte model seems to be able to overclock once the BIOS is updated. It's limited in voltage but that Pentium is a lower power chip so you should have some headroom. I wouldn't go crazy or anything, but if you can squeeze a little extra time out of that system you might buy enough time for some better upgrades to come down in price.

 

[rgd1101]

why going back 2 generation?

 

[iosif_betsis]

First question is how much money you have to spend for the new system?
Second 8gb ram is enough for gaming I don't no what programs running in background and what settings you have in game for graphics?