RAM Problems

I have a Dell optiplex 780SFF running Win7 Ultimate x64.

The DDR3 Ram currently installed is only 2GB (2x1GB sticks).

I bought Corsair XMS3 ram. 4 sticks each of 4GB. 1333 MHz.

Trying any permutations just causes the pc to run its fans but it won't boot.

The Dell manual states that this configuration is OK. I should be able to run 16GB and the machine should run 4GB sticks.

Am I missing something?

I've previously changed RAM over the years and it was just plug and play.

Do I need to change BIOS settings? I flashed the BIOS with the latest A14 one.

Check the voltage spec on the new and old RAM. Are they the same?

You could have a defective stick of RAM. Try installing them one at a time in the first RAM slot.

Voltage is 1.50V on both.

I'll try the sticks as you describe.

I thought the Optiplex has dual channel RAM slots. One pair is white, the other pair black but I'll try 1 at a time and then 1 pair.

Report back shortly.

Thanks.

Yes, dual channel. But that doesn't mean you can't install one stick. It will just run in Single Channel mode rather than Dual Channel.

If your sticks are installed exactly where the other two sticks were installed then you have the slots correct. Some PC manufacturers have some odd slot/color/number conventions - always best to check the manual.

If you are adding these new sticks in the open slots along with the old ones you should tell us.

Well, well.

I tried all 4 sticks in slot 1, 1 at a time. 3 sticks OK, 1 not.
Then tried the "1not" with another and fault appeared. Etc.

So, I've got 1 faulty stick.
As soon as I put it into the pc in any of the 4 slots, the pc won't boot and the indicator lights on the Dell front panel show steady 1 and 3, meaning RAM fault.
Looking at the ram stick there's nothing obvious.
I may just have to send it back to Amazon.
Should I try and do anything else?
I'm wondering about wiping the gold contacts with a piece of paper, or something.
Many thanks for your help so far.

What a cracking Forum this is.
Thanks folks.
I gave the faulty RAM stick a quick wipe over the gold contacts. No good so it's going back to Amazon.
A bit surprised, really. It's not cheap so I expected it to have been tested.
Thanks again.

No, not that uncommon. Happens all the time.
They might test the sticks, but things can happen between them and your mailbox.

In modern manufacturing some companies accept a 5% failure rate as acceptable. They think it is cheaper to replace the defective part than improve manufacturing tolerances.

Good job testing it out. At least now you know it's not you!