Asus P5W-DH problem...

[ajm786]

I got 2 more of the exact same memory and figured to just install it and I'd be good to go, since the memory is running at its default speed.

 

Wrong.

 

Going 4 x 1GB totally ruins my OC. I have to lower the FSB to the lower 300s instead of the 410 that I'm running at, or run the memory at DDR2 600 speeds, which would put me below 1:1 from the FSB and make my memory a bottleneck. BSODs and crashes galore. No amount of tweaking any other options could get it to run properly.

 

I just went out and bought some Corsair 2 x 2GB DDR2 800 TWINX2X4096-6400C5 G memory after some research, of which I came to the conclusion that 4 x 1GB is too strenuous on the MCH.

 

I got the memory installed it, and the system does not boot at all. Reset BIOS, adjusted every single possible setting. No go.

 

Finally I did something that we enthusiasts don't normally do: I allowed the motherboard to detect timings on the memory (TWINX2X4096-6400C5 G) automatically, and, would you know it, the system booted right up.

 

Now the problem is that I cannot stabilize the system no matter what. No voltage setting, no timing adjustment, nothing.

 

What's going on?

 

Here's my system:

 

Corsair 620HX PSU * Asus P5WDH * Core 2 Duo E6420 @ 3.28 w/Thermalright Ultra 120 Extreme, cooled w/Sony Scythe S-Flex SFF21F * Corsair TWIN2X2048-6400 * WD5000KS, HD160JJ, SP1614C SATA; Toshiba SD-M1712; Optiarc AWG170S-B2 * EVGA 8800GTS * Highpoint RocketRaid 2300 * X-Fi Platinum; WinTV Go * Razer Deathadder/Logitech MX518 * CM Stacker 830 * Dual LCD (Viewsonic VP201b & Viewsonic VX922)

[DerekT]

The motherboard memory controller can not keep up with the extra DRAM at the rated 6400 speed. You will need to drop the speed of the DRAM from 800Mhz to 667Mhz. If you had purchased 4 X 1024MB of PC8500 (1066Mhz) DRAM, then you would have had to drop to PC6400 (800MHz) 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.

 

You will as noticed ruin your overclock by quite a large margin. You would need 4 X 1066MHz DRAM to gain that clocking back. This is a motherboard chipset issue and you can log onto any website that helps people with boards/memory and see a plethora of posts with people having the same issue.

[ajm786]

The motherboard memory controller can not keep up with the extra DRAM at the rated 6400 speed. You will need to drop the speed of the DRAM from 800Mhz to 667Mhz. If you had purchased 4 X 1024MB of PC8500 (1066Mhz) DRAM, then you would have had to drop to PC6400 (800MHz) 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.

 

You will as noticed ruin your overclock by quite a large margin. You would need 4 X 1066MHz DRAM to gain that clocking back. This is a motherboard chipset issue and you can log onto any website that helps people with boards/memory and see a plethora of posts with people having the same issue.

 

Sorry...did you read my entire post? :o: I already thought of what you just stated. That's why I went out and bought TWINX2X4096-6400C5 G. This is 2 x 2GB. It still doesn't work. I can't stabilize the system.

 

Even if I drop the speed of the memory to DDR2 600, the system will not boot. The only way I can get my system to boot with the memory in it is to either drop the FSB that I'm running at (400FSB), or make sure that Auto SPD Configure is enabled rather than how we usually do it (setting it manually). Even then, the system crashes all over the place. It won't even pass Memtest, with a single module or with them both installed.

 

Right now, I'm running 2x1GB Corsair PC6400 memory at DDR820, with my CPU FSB being 410; this is 24/7 stable, and I've been running this way for over 4 months. I was told by Mike Clements, a Corsair rep, on another forum, that electrically, 2x2GB is similar to 2x1GB. If this is the case, why is the 2x2GB I just bought not stable at all?

[DerekT]

Sorry...did you read my entire post? :

 

My mistake. It was a late night last night and I skimmed. I read that you had a second set of sticks and passed on to my answer. Please excuse it.

 

Have you set your DRAM to 2.1V with the 2 X 2048? You might wish to try a reset of your CMOS by loading system defaults, saving system defaults, setting the DRAM to 2.1v. No CPU overclock and see if you get in. Then you may have to redo your overclock as it easily might not be as high as 410 FSB.

 

You might well have to find the new overclock spot with this new DRAM.

[ajm786]

My mistake. It was a late night last night and I skimmed. I read that you had a second set of sticks and passed on to my answer. Please excuse it.

 

Have you set your DRAM to 2.1V with the 2 X 2048? You might wish to try a reset of your CMOS by loading system defaults, saving system defaults, setting the DRAM to 2.1v. No CPU overclock and see if you get in. Then you may have to redo your overclock as it easily might not be as high as 410 FSB.

 

You might well have to find the new overclock spot with this new DRAM.

 

Yes, I tried ALL that. Set the RAM to 2.1V, reset BIOS, flashed to newer ones, everything. As I pointed out earlier, I could get in fine with the FSB at 266 or 320, or in between. Nothing above.

 

So this is still a limitation of the chipset?

[RAM GUY]

320 Is a good over clock for that MB, so yes its just the limit of that platform.