Hynix drivers I not have a driver for them

http://www.skhynix.com/ssd/en/html/Firmare.html

Hynix does not have any kind of consumer warranty as they usually sell to OEM builders such as Dell or HP. As such they deal in very large volumes or product.
On their website they state that they offer no direct consumer warranty, and recommend going through the seller for any warranty support.
I would recommend pursuing your warranty claim with whomever is providing it (whether it is a retailer such as best buy, etc. or direct through the manufacturer such as Dell or HP) I believe hynix is located in China so it might be very difficult to go through them anyway.

It sounds like a speed issue, in the difference between the 4200 and 5300.

There isn't one, Hynix is just a chip manufacturer, they don't have service centers.

your system does not support the dual ddr ram unless you have a add-on VGA card

I have included the link to the user manual ... see chapter 1 section 1-1 Features and Specifications

Abit NF7-S v2


Supports DDR 400 only when using an add-on VGA card (NF7-M)

yes, the ram is backwards compatible.

RAMs are not compatible...
if u have MSoffice 2007, there is tood there in that u can use that to check the RAMs comaptibility...go to
Start/All Programs/MS Office 2007/MS office Tools/MS office Diagnostics

Else u can downlaod a RAM checker from google

og to www.hynix.com and you can find the software.. try it

Maybe due to some virus/malware running in the background. Also, can u let us know the OS/ antivirus software u are using

Have you tried installin the memory in various slow...ie 1,2/1,2/1,4 etc?
Its sounds like your mother board is unable to run the sticks at the rated speed as they are different brands and densities so its dropping the speed to 166.

Have you tried going into the bios and changing the ram speed there?
Also try changing the command rate from 1T to 2T to see if that helps.