GA-P55A-UD3 Dual channel RAM problems

[SkyNT]

GA-P55A-UD3 rev 1.0 (factory default BIOS)
i7 860
Win 64-bit
Saphire ATI HD 5770
2x2GB Corsair 1333MHz DDR3 TW3X4G1333C9A
2x1TB WD in RAID 0
No overclocking

I am trying to upgrade the RAM with a second pair of 2x2GB Corsair 1333MHz DDR3 TW3X4G1333C9A for a total of 4x2GB (8GB).

The first new set of 2x2GB Corsair 1333MHz DDR3 TW3X4G1333C9A was defective as one of the sticks kept crashing my computer (i'm hoping this didn't cause any kind of damage....). Before crashing, the mobo did register all four sticks on both channels for a total of 8GB (usable)

I RMA'ed for another pack of 2x2GB Corsair 1333MHz DDR3 TW3X4G1333C9A. These sticks are OK as they don't crash the computer and I can replace the old ones with the new ones and everything is working fine.

However if I place the new sticks along with the old sticks, the mobo only registers 2 of them (Windows displays "8GB (4GB usable)"). BIOS also sees all 4 sticks but does not use 2 of them. If I put 3 sticks instead of 4 then I have all 6GB usable which leads me to believe there is a problem with my dual channel configuration...

Any suggestions? Should I update my BIOS to F11? I don't wan't to mess with my BIOS unless I really really have to.

Thanks.

[Dark Mantis]

There is no problem with your Dual Channel it is simply that you still are trying to run on Auto. You have added to the pressure on the memory controller and need to up the memory voltage to compensate. Try adding 0.05V to whatever your default voltage for your memory is. You may also need to up the QPI/Vtt voltage a little to keep up as it must stay within 0.5V max of the memory voltage.

[SkyNT]

Hi and thanks for your reply.

The normal voltages are:
Vcore 1.216
QPI/Vtt 1.1
DRAM 1.5

I tried DRAM up to 1.65 with QPI/Vtt to 1.33 and two of the sticks are still not usable.After that it's ... uh pink letters

To be precise, it's DIMMs 1 and 2 that are not usable.

I'm pretty sure my timings are 9-9-9-24 (Auto)

[Lsdmeasap]

Remove your CPU and check the socket for bent pins, if you are unsure please post some images here in a well lit room without flash.

[Dark Mantis]

Do as Lsd asks and post some decent photos here for us to check for you and also download and run Memtest86+.


Memtest86+        http://www.memtest.org/

Insert one stick of memory in slot 1 and run Memtest on it for at least 10 loops and if there are no errors then swap it over with the next one and continue untill you have checked all  modules.

If you have any errors the module is faulty.
 
If you have any faulty modules you will have to return the whole kit as they are matched.

Post back when you have done that with the results.

[SkyNT]

Hi

I guess I forgot to mention, I ran memtest86+ for all my modules and nada. The funny thing is, as I mentioned earlier, I can put any combination of three of the old and new sticks into any of the first two and third or fourth slots, and they all work, but as soon as I put the fourth one in, then two of them become unusable. And it's always DIMM's 1 and 2 regardless of which module was put where.

I doubt this is relevant, but despite being identical model numbers, the new modules are rev 3.13 while the old ones are 1.something.

I guess the next step is disassembling my CPU. As this is a somewhat involved procedure, the earliest I can report back is tomorrow.

Thanks.

[Dark Mantis]

It might be that you Uncore setting is wrong. What is it set to at present?

[SkyNT]

I do not have access to a camera so I can't post pictures of my CPU slot, but I did not detect any physical damage.

My Uncore reads 18x @ 2400Mhz in the Advanced Frequency Settings (just under QPI settings). I read somewhere that it should be twice as much as the memory frequency which is 1333. I'm not sure how to change it either way.

Thanks.

[Dark Mantis]

You have the right idea just wrong information.

It should be twice the memory multiplier (not frequency). When using x8 memory multiplier you need to set uncore to 2x that or 1-2 above, so x16-18.

If using a x10 memory multiplier you would set x20-22 uncore