Need advice on upgrading Kingston hyperx blu ram

Here are my system specs:
Amd phenom 2 x4 965 Black Edition 2
Asus motherboard m4a87td evo
Memory : Kingston Hyperx blu ddr3 cl9 1600mhz KHX1600C9D3B1K2/4GX 1.65V 2*2gb
Graphics : Nvidia Geforce Gtx 550 Ti
Im playing World of Tanks at medium settings but performance is quite disappointing so I'd like to upgrade ram. I search for the ram on ebay and amazon(uk) but its a ghost town( I cant find much options and far to dear when I find exact model).Would a different brand of ram with the same specs work with my ram? I'd like to upgrade to 8gb.Also does voltage matter 1.65V and 1.5V.All newer cards are 1.5V.Would my processor support 1600mhz?As far as I know my motherboard supports up to 2000mhz.
Oh I also run some heavy applications like Solidworks and AutoCAD.
All advice is appreciated. Thanks in advance:)

Voltage matters.

Another brand with identical specs might work, but the standard advice is to buy all new RAM if you can't get the same brand and model that you now have. There is some risk in combining different brands.

But the more important questions are:

Why do you think more RAM will help? Do you know that you are using all of the 4 GB?

Going from 4 GB to 8 GB might help, but gaming performance is much more dependent on the video card.

I didn't see where the version of Windows is 32-bit or 64-bit, makes a difference.

Yes, voltage does matter. Some of the new Notebook motherboards and RAM modules use 1.35V but a few can autoswitch between 1.5V and 1.35V but what I see for your Desktop calls for 1.5V. Usually using higher voltages is called overclocking, can work fine but also can kill parts.

AMD Processors for Desktops: AMD Phenomâ

Crucial says you can use up to 16GB maximum RAM. Here's the list:
Computer memory and SSD upgrades for ASUS ASUS Motherboards M4A87TD EVO from Crucial

[QUOTE=CasualGamer089;3019501]Here are my system specs:
Amd phenom 2 x4 965 Black Edition 2
Asus motherboard m4a87td evo
Memory : Kingston Hyperx blu ddr3 cl9 1600mhz KHX1600C9D3B1K2/4GX 1.65V 2*2gb
Graphics : Nvidia Geforce Gtx 550 Ti
Im playing World of Tanks at medium settings but performance is quite disappointing so I'd like to upgrade ram. I search for the ram on ebay and amazon(uk) but its a ghost town( I cant find much options and far to dear when I find exact model).Would a different brand of ram with the same specs work with my ram? I'd like to upgrade to 8gb.Also does voltage matter 1.65V and 1.5V.All newer cards are 1.5V.Would my processor support 1600mhz?As far as I know my motherboard supports up to 2000mhz.
Oh I also run some heavy applications like Solidworks and AutoCAD.
All advice is appreciated. Thanks in advance:)

Edit :
Yeah graphics card might be the problem. I searched on worldoftanks.eu forum and NVidia GeForce gtx 550 Ti was suspect for low performance. But again 8gb will future proof my pc for further use. After all games are getting more hungry for specs. So what graphics card should I get?
I would prefer NVidia but Amd is an option. I found this Asus Nvidia GeForce GTX 750 Ti Graphics Card (2GB, GDDR5, PCI-Express 3.0) on amazon.uk with a good price too.
Would it be compatible with the motherboard?