Add more memory or replace existing?

[will2power]

Been a while since I last posted, since I had great help here with building new PC over 6 years ago (still running!) thought I would come back.

I have...

ASUS P7P55D-E EVO motherboard Slots:4 (2 banks of 2)
Intel Core i5 750 @ 2.67GHz
4.00GB (2x2GB) Corsair Dominator Dual-Channel DDR3 (9-9-9-24)
1024MB ATI AMD Radeon HD 5700 Series

It is an old system now and outdated, especially memory, I want to boost to at least 8gb.

After some research here I believe...

Corsair Vengeance is better than Dominator (cheaper, newer)
I was thinking to add 2x4gb Vengeance to the main 2 slots and run old memory on others for 2x4 and 2x2, 12gb total, is this possible/ recommended?

As memory is cheap these days could possibly just get a kit and discard older memory, if it is likely to save problems, this would not limit me to Corsair and compatibility restraints.

Look forward to hearing some recommendations, memory upgrade is long overdue!

Thanks in advance

 

[CountMike]

Replacing memory is better option as adding more even of same make doesn't guarantee they would work together properly. 8GB should be just fine for that setup.

 

[will2power]

Thanks CountMike, I will get 8gb memory and add.

Final question, would you recommend getting Corsair Vengeance at same frequency and trying to use with the existing just in case it works? Or is there better/cheaper memory out there.

When I bought the Corsair there was a lot of backing for it from members of this site. It has done very well but not sure Corsair is still way to go. Also curious about the DDR3 vs DDR4 and 1333htz vs 1600htz, not sure there will be much difference on an old set up but guess it leaves options to upgrade in future?

Thanks for your reply

 

[CountMike]

Make of RAM is not much of a concern with DDR3. If you can get Corsair with same specs as yours (frequency, voltage and Cl) you would have more chance to work with OLD one.
Not much or any perceptible difference between 1333 and 1600MHz either but for same price 1600 has slight advantage specially if overclocking CPU.
DDR3 and DDR4 are not compatible of course but if making new computer it makes sense to go with ewer one. In the future at least there should be a lot of improvement with DDR4 over DDR3.