MSI K9N Platinum and CM2X1024-6400C5DHX - won't boot

Hello, my mainboard is MSI K9N Platinum (MS-7250) with the latest BIOS. I've been using it with two Corsair XMS2 modules CM2X1024-6400 (CL5) for more than a year now, which gave me 2GB of memory. They were both working perfectly, no problems at all.

Now, I decided to get myself another 2GB, so I picked 2 x CM2X1024-6400C5DHX.

After inserting them, I came to the sad realization that my PC is not booting with them. I have a 2x2 LED display which shows current state of POST and it stops at "Memory Detection Test". All fans are working, but there's only black screen.

I tried booting with only single stick, no luck here... tried with the other one, nothing. I tried both of them, same result.

I even tried setting my BIOS to the settings from this thread, still nothing.

Resetting CMOS didn't help either. It's worth noting that both my old sticks are working perfectly fine, so I don't think there's anything wrong with the mobo.

I also tried them on some other motherboard (GA-EP43-DS3). The result was that it booted for like 5 seconds, and kept restarting.

Does that mean I should forget about getting them to work? Or maybe I could try changing settings in my BIOS?

Here's the info from the new sticks:

CM2X1024-6400C5DHX

XMS2-6400

1024 MB

800 MHz

5-5-5-18

1.80V ver4.1

10403377

It's the same on the other stick.

I'll just add that my old sticks have the same timings, same frequency, and voltage is also the same.

However, I don't this should matter right now since I didn't even try to mix them with the new sticks yet, that means the problem is with those new sticks.

In my BIOS, I can change the following settings:

MCT Timing Mode [setting to manual gives me those settings]

Bank Interleaving [Enabled]

Enable clock to all DIMMs [Disabled]

CMD-ADDR Timing Mode [2T]

SoftWare Memory Hole [Enabled]

I can also adjust frequency and voltage.

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Please note: I cannot access my (and the other) computer with any of the new sticks, so performing any memtest on them is out of question right now, sadly...

Thanks in advance for any help! Of course I can provide more info if you need it!

You posted this after we closed on Friday night and we are closed on the weekends so that is why you did not get a reply.

Oops, sorry for that.

I would try and clear the BIOS with just one of the new modules and see if it will post

Tried doing that already, no luck with any of the modules. Tried also lowering frequency to 667, wouldn't help either.

I'm almost sure they're faulty, but at the same time I remember someone writing here that it's extremely unlikely for both modules to fail at the same time, so...