Using More than 2GB with Maximus Extreme

[MarkTwo]

I have recently upgraded my PC with the Asus Maximus Extremeand Intel Core 2 Extreme (QX9650), I have also bought 2 sets of TWIN3X2048-1333C9DHX, being 4GB in total. Everything works fine with 2x1GB sticks but the moment I introduce the other 2x1GB the system will not boot and fails on "DET DRAM" (The memory seems ok as it does not matter which of the two pairs I use first, it starts). I have upgraded the BIOS to the latest version (1001). I am not interested on overclocking anything I just want to use 4GB of RAM (I play around with large pictures so its useful to have more than 2GB)

 

Any help gratefully received

[eagle107]

It looks like you might have the same problem as I do with my Asus P5N-D motherboard. I cannot put two match pair Corsair TWIN2X4096-6400C4DHX modules in all four RAM slots. I am not sure why you cannot do this Corsair memory, but the Asus manual states you might be able to put Kingston memory in all four RAM slots. Maybe someone on this forum can explain why you cannot put Corsair match pairs in all four RAM slots on the Asus motherboards.

[Wired]

eagle107: You can, and people have successfully ran 4 sticks in Asus mobos.

 

MarkTwo: Try underclocking your memory a step, down from PC3-1066 to PC3-8500.

[Cannyone]

I'm having a very similar issue with an Asus P5E (same chipset as that Maximus Extreme - but mine uses DDR2). The memory in question consists of two matched pair of Twin2X2048-6400C5DHX modules. I specifically chose these modules because they are spec'd to run at 1.8v. Which is the standard DRAM voltage for this motherboard. And there was a part in the manual which states that if I tried to use 800MHz modules with SPD timings set to CAS4, the memory speed would automatically be dropped to 667MHz.

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So now, if I understand Wired, I should drop the speed a bit before I install the modules and all 4 will work? Will I then be able to bump the speed up a bit, or will I be stuck at that lower speed? TIA! :biggrin:

[DerekT]

down from PC3-1066 to PC3-8500.

 

1066 = 8500 or PC3-1066 (PC3-8500)

 

So 1066 = 8500 whether PC2 or PC3....

 

@Cannyone

 

The on motherboard memory controller has to access double the slots and double the DRAM capacity when you add two more sticks to the system. It can not easily keep up with the extra DRAM at the rated speed. You will need to drop the speed of the DRAM from rated speed to one bin lower. ie If you purchase 4 X 1024MB of PC6400 (800Mhz) DRAM, then you drop to PC5300 (667MHz) DRAM, etc. 2 X 2048 will not issue this problem. This is a problem of all 4 banks being populated.

 

Think of it this way. If you have a small phone book, then when you go into the index to find the page where you will find the phone number you are doing so at a certain speed due to the pages of the Index. Then you have to drive through the pages to get to the number. Now if your index is twice as large and the pages twice as many, then it takes longer to access the data. Now DRAM has a Strobe and the length of the strobe is how long the rows and columns can be left open before they must be refreshed. There is not enough time for the dram to be refreshed and then accessed with 4GB at the full access speed of the DRAM. The chipsets are optimized for 2GB, not 4GB and for 2 DRAM slots, not 4 DRAM slots populated. You can overclock the FSB (and hence the Memory Controller Hub = MCH) to gain some extra bandwidth and thus access the capabilities of the DRAM since the chipset is now clocked up. Usually when you clock up the FSB and concurrently the Memory Controller Hub (MCH) you need to raise the voltages of the CPU/MCH a bit as well.

 

So if you overclock the CPU, then you concurrently raise the speed of the MCH/Northbridge (Memory Controller Hub) and the speed of the DRAM.

 

 

To find out the overclock values, use the ratio (for 1066MHz FSB CPU)266:667 as x/800. Cross multiplication gives you a FSB of ~319MHz.

 

So if you took a 1066MHz FSB Core 2, say a Q6600 and 4 X 1024 sticks of 800mhz, dropped the DRAM speed to 667Mhz, raised the CPU FSB to ~320Mhz, then you would have a CPU speed of 320 X 9 ~= 2.88Ghz and DRAM speed of ~800Mhz. Use memtest to be certain that your system DRAM @ 800Mhz with 4 X 1024 is stable. Then use Prime95 to test your system stability once you enter Windows.

[Cannyone]

1066 = 8500 or PC3-1066 (PC3-8500)

 

So 1066 = 8500 whether PC2 or PC3....

 

@Cannyone

 

...<snip>...

 

So if you took a 1066MHz FSB Core 2, say a Q6600 and 4 X 1024 sticks of 800mhz, dropped the DRAM speed to 667Mhz, raised the CPU FSB to ~320Mhz, then you would have a CPU speed of 320 X 9 ~= 2.88Ghz and DRAM speed of ~800Mhz. Use memtest to be certain that your system DRAM @ 800Mhz with 4 X 1024 is stable. Then use Prime95 to test your system stability once you enter Windows.

 

Ok! All of that makes sense to me. But my question is: Do I simply lower the DRAM speed, power off, then install the second pair of modules?

 

Hmmm.... come to think of it. I better burn a new copy of MemTest to a CD. I've heard on the Asus forums that the current BIOS revision has issues with Memtest, but I guess I'll find out.

 

I guess the serendipitous side effect of this is that I'll have an Overclocked CPU again. :biggrin: I don't really "need" to overclock, but I do have lots of experience. Thanks Again!

[Cannyone]

Ok, that didn't work! :sigh!:

 

I also bumped the voltage, though I didn't bump the voltage on the Northbridge.

 

Any suggestions as to what I might try next?

[RAM GUY]

What were the exact settings you had set?

[Cannyone]

The modules are 800MHz modules - so I set the memory frequency to 667MHz. And I had previously set the voltage to 1.9v, up from the standard 1.8v. All other settings were at "Auto".

 

I was going to try and find out how other settings, like: Ai Clock Twister, and Transaction Booster, affected this situation. But Asus support aren't very responsive. They only seem proficient at "passing the buck", and doling out the pat answers.

[RAM GUY]

Please make sure that you have the latest Bios version and then load setup/optimized defaults and set the Dim Voltage to 1.7 volts (+.3 Volts W/Giga-Byte) and then set the timings manually to the tested settings for the specific module you have, and then test the module/'s one at a time with http://www.memtest.org! If you still get errors, please follow the link in my signature “I think I have a bad part!” and we will be happy to replace them or it! However, if you get errors with both modules that would suggest some other problem and I would test them in another system or MB to be sure. In addition, with some MB's (Mostly ASUS) you have to disable legacy USB in the bios when running any memory test.

[Wired]

1066 = 8500 or PC3-1066 (PC3-8500)

 

So 1066 = 8500 whether PC2 or PC3....

Bah, typo, meant from PC3-10666 to PC3-8500. I know, didn't look right either, got confirmation that those are right from a better source, I thought the Corsair website was wrong!

 

@Cannyone: DerekT and Ram Guy gave you the info you need :)

[Cannyone]

Please make sure that you have the latest Bios version and then load setup/optimized defaults and set the Dim Voltage to 1.7 volts (+.3 Volts W/Giga-Byte) and then set the timings manually to the tested settings for the specific module you have, and then test the module/'s one at a time with http://www.memtest.org! If you still get errors, please follow the link in my signature “I think I have a bad part!” and we will be happy to replace them or it! However, if you get errors with both modules that would suggest some other problem and I would test them in another system or MB to be sure. In addition, with some MB's (Mostly ASUS) you have to disable legacy USB in the bios when running any memory test.

 

Um, none of that works for me!

1. I do have the latest available BIOS for my motherboard. (ver. 0601)

2. There are no "optimized" defaults just a "setup default" option. I used that...!

3. I can't set the DIMM voltage to 1.7v - it's either "Auto", 1.8v - on up, in 0.02v increments. I used 1.9v.

4. I set all the settings for the modules manually. There were some slight differences.

5. The BIOS options for memory, like; AI clock twister and Transaction Booster, I set for greatest "compatibility".

 

The problem persists, and the system fails to POST. Other people tell me that they have no problems running 4 modules in this motherboard. That memory isn't necessarily Corsair Brand Memory, but it's not some "chipset limitation", or some bug in the BIOS. At the same time either "pair" of modules works fine. So I doubt either set, purchased separately, but both purchased recently (within the last 60 days) is "bad".

 

I have allot of experience building computers. My instinct tells me it's the motherboard, and I have a different board but that one has a different chipset. So I'm really reluctant to swap it out. I guess I'll just have to make a new drive image (just in case...).

 

It's also really sad that you can't get "quality tech support", even from supposedly reputable companies.

 

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Edit:

I tried using "Tech Support Express" link and that was more of the same stuff I got from Asus. Namely "pat answers", because no one "living" can take the time to read enough, and think just a bit, so they can understand my problem. Now I've worked Tech Support before so I know that they want you to be "efficient", but in fact you end up being completely inefficient. It would be better to .... FORGET IT!!

[RAM GUY]

All we can offer would be to replace the modules for you, there is some problem obviously and if what we have said does not help them let's get them replaced, please use the On Line RMA Request Form and we will be happy to replace them.