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Problem with TWIN2X4096-6400C5C and Asus P5K mobo


Sirgin

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Hello all,

 

I recently bought a set of Corsair TWIN2X4096-6400C5C DDR2 memory and cannot get it to work properly with my vanilla Asus P5K motherboard.

 

I bought this RAM as an upgrade from what I've been using so far: 2x1GB 667Mhz memory of a brand called Transcend. This is cheap/value RAM, but it has always worked (in Dual Channel mode).

 

2GB RAM was starting to feel insufficient, especially in Vista (64bit). I figured upgrading to 4GB 800Mhz RAM would be good, so I bought this set.

 

When I put the RAM in and started up my computer I got nothing. All the fans started spinning but the screen remained black (No POST or anything).

 

I then took out the second module and *woohoo*, it worked (Single Channel). This was with all settings in my BIOS on "Auto".

 

Then I manually set all the settings (DRAM speed, latencies and voltages) to what it said on the RAM. It still worked (with just one module).

 

Then I switched out the first module (which worked) for the second module and tried it. It didn't work, got a black screen again with all fans blazing.

 

Then I figured maybe I needed a bit more voltage for the RAM to work. I switched back to the module that had worked before and changed the vDRAM from 1.80V to 1.90V. It worked.

 

Then I put in the 2nd module again (with those settings) and it still didn't work.

 

Am I simply unlucky and have I got a defective RAM module (the second one) or is there something I should try that I haven't tried yet? Please note that I'm not a computer/BIOS expert in case the solution is very obvious.

 

This is what it says on the side of each RAM module:

CM2X2048-6400C5C

800Mhz 2048MB 5-5-5-18 1.80V ver4.3

 

I specifically avoided buying RAM with higher speed/lower latencies because that can sometimes give problems...yet with this pretty "standard" RAM I still can't get it to work. Needless to say this is quite annoying.

 

Before posting this thread I read a couple of others where I also saw people having trouble with their RAM, but almost all of those are problems with higher speed (1066Mhz) and lower latencies RAM, or people trying to get 4 modules to work, all of which doesn't apply to me.

 

Any help would be immensly appreciated.

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I'm trying really hard to get to the bottom of this and saw this in an information thread by RAMGUY:

 

Twin2x4096-6400C5

........................XMS640X v1.X...MICRON........128Mx8

........................XMS640X v2.X...QIMONDA......128Mx8

........................XMS640X v3.X...ELPIDA.........128Mx8

........................XMS640X v4.X...MICRON........128Mx8

........................XMS640X v5.X...PSC.............128Mx8

 

Then I read my ASUS P5K's manual again (or atleast the RAM section) and found:

 

This motherboard does not support memory modules made up of 128 Mb chips.

 

Is this the reason why the RAM doesn't work? Could anyone please confirm or disconfirm this?

 

If so, I do find it odd that one of the sticks works flawlessly, and the other one doesn't even allow my computer to POST.

 

What are my options for running 4GB of RAM if I have to avoid 128MB chips? 4x 1GB? (aka 2 sets of 2GB dual channel?)

 

I'd really appreciate any help.

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If I'm reading your post correctly, it sounds like you've tried each module individually in the same socket. If one module works and the other ('2nd' in your case) doesn't with everything else the same, that's a pretty solid troubleshooting job in my opinion. At this point, the '2nd' module has never been involved in a working setup, right?

 

You could fight with the '2nd' module to run in some less than advertised speed/timings, but with your simple configuration, I'd expect it to run at stated timings. Ram Guy will confirm this, but I'd guess you're looking at an RMA, especially if its not working at all. Luckily, Corsair's lifetime warranty is great and they stand behind their product.

 

I just saw your new post. I'm looking at the Asus website and it says "4 x DIMM, Max. 8 GB, DDR2 1066*/800/667 Non-ECC,Un-buffered Memory". This would suggest that 2GB modules are supported. The 128Mbit chips are 8 bits wide, so you get 128MByte per chip (actually 1 Gbit per chip). To get to 2GB, your modules are probably structured as double sided, with 8 chips per side. 2 sides x 8 chips/side x 128MByte/chip = 2048 MByte = 2GByte. I haven't seen a module with more than 8 chips per side in years, so this is pretty much how it has to be. I've seen "xxxMb x 16" chips that might not be supported... This would only need 4 chips per side ... or a single side with 8 chips, but this isn't your case. I was trying to download the Asus manual, but its going too slow... see if this info helps.

 

Good luck!

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If I'm reading your post correctly, it sounds like you've tried each module individually in the same socket. If one module works and the other ('2nd' in your case) doesn't with everything else the same, that's a pretty solid troubleshooting job in my opinion. At this point, the '2nd' module has never been involved in a working setup, right?
That is correct. I tried each module individually, in the same socket. One works, giving me 2GB of memory (obviously), and I can run it at the specs that it needs to run at (800Mhz, 5-5-5-18, 1.8V).

The other module doesn't work at all. No POST, no BIOS, no nothing. If I combine the two (putting them both in, in Dual Channel setup) then I get the same result as with only the second module: no POST, no BIOS, no nothing. The screen remains black. It's like the second module "corrupts" everything when it's there and as a result I can't do anything.

 

You could fight with the '2nd' module to run in some less than advertised speed/timings, but with your simple configuration, I'd expect it to run at stated timings.
Yeah, that would be a bit stupid, seeing as it's "only" 800Mhz RAM and not 1066Mhz...the motherboard should be able to handle this. (And it has proven it does, with the first module, that is).

 

 

I just saw your new post. I'm looking at the Asus website and it says "4 x DIMM, Max. 8 GB, DDR2 1066*/800/667 Non-ECC,Un-buffered Memory". This would suggest that 2GB modules are supported. The 128Mbit chips are 8 bits wide, so you get 128MByte per chip (actually 1 Gbit per chip). To get to 2GB, your modules are probably structured as double sided, with 8 chips per side. 2 sides x 8 chips/side x 128MByte/chip = 2048 MByte = 2GByte. I haven't seen a module with more than 8 chips per side in years, so this is pretty much how it has to be. I've seen "xxxMb x 16" chips that might not be supported... This would only need 4 chips per side ... or a single side with 8 chips, but this isn't your case.
Exactly. Before buying this RAM I looked at what the maximum capacity of my mobo was. I saw it was 8GB so I assumed it would take 2GB modules with no problems, because it has 4 RAM slots. I only found out about the "no 128MB chips" thing today. I can't really blame myself for that...who in the world would check their manual to look up such an obscure characteristic like that? I bet no one does.
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If I remember from the product page for this motherboard, its a P35 chipset, right? That what I'm running, and I'm using 4x2GB TWIN2X modules right now.

 

I don't know if I'd get so hung up on the '128Mb' note in the Asus documentation. The board obviously works with a single '128Mb chip based' module. If one module works, then you swap it out with the other, I'd point the finger at the suspect module.

 

In general, some people using 'chips' and 'modules' interchangeably. I like to think of a 'module' as a collection of RAM ICs (chips), the SPD register, and other logic on a PCB. I try to stay consistent to avoid confusion... Asus may not be so consistent with their documentation. 'Mb' and 'MB' can also be used incorrectly very easily... so run their use through a 'sanity check' filter.

 

At this point, I'd still lean towards you having one good module and one bad module. If you have another DDR2 computer... try the 'suspect' module in there alone. See if its still a no-go. If Ram Guy doesn't post a response here, you might want to post in the warranty section to see if he agrees.

 

Good luck!

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