Unpredictable results with QUAD2X4096 and Gigabyte X38-DS5

Hi All,

This is my first post here so be nice :).

My problems are very similar to those experienced in this thread...

http://www.asktheramguy.com/v3/showthread.php?t=64181

..but as I am using a different mobo, I thought I would add a new thread.

I will start off by asking a simple question. Have I made a mistake with the Gigabyte X38-DS5 and the QUAD2X4096? Are the two compatible? I have noticed that Gigabyte have released about 5 BIOS updates in a month 2 of which relate to memory performance and 1 specifically to the use of 4 x DIMM's.

Essentially, if my system boots (Vista64), it works without a glitch. However sometimes I get a BSOD where the Microsoft logo should be. Sometimes I get a 'file corrupt error' and sometimes the thing just restarts without even trying :-). If I set the memory timings to the advertised 5-5-5-15-2T, I do not have a chance!

I've just set up this system so I'm in a good position to return parts if needed. Any thoughts?

TDCat.

I will start off by asking a simple question. Have I made a mistake with the Gigabyte X38-DS5 and the QUAD2X4096? Are the two compatible? I have noticed that Gigabyte have released about 5 BIOS updates in a month 2 of which relate to memory performance and 1 specifically to the use of 4 x DIMM's.

 

I've just set up this system so I'm in a good position to return parts if needed. Any thoughts?

Have you set the DRAM to 6400Mhz?

Hi,

If by 6400 you mean 800MHz rather than the advertised 1066MHz, yes I have tried that and everything seems to be fine. I haven't noticed any faults whatsoever at this speed. In fact, I can also set the timings to the correct 5-5-5-15 at 800 and all is OK.

Hey, it's not the end of the world if I need to run this at 800 rather than 1066, it's just the fact that it bugs me a little to spend 200.00 GBP on quality memory only to have to run it at a lower speed than advertised.

My mobo setting has the memory speed at 333x2.4. Is it OK to use another setting to maybe take it up to 333x3.0 and try it at 1000MHz. I know the memory should be OK but I was just wondering whether this is OK to do on the motherboard as it states only certain multipliers are for certain FSB's (e.g 2.4B 2.8B etc).

I've read a lot about problems with 4 sticks and generally difficulty addressing them. Is this a motherboard limitation or is it a case of the memory really just having trouble doing what it says on the tin?

TDCat.

I've read a lot about problems with 4 sticks and generally difficulty addressing them. Is this a motherboard limitation or is it a case of the memory really just having trouble doing what it says on the tin?

The memory controller can not keep up with the extra DRAM at the rated 8500 speed. You will need to drop the speed of the DRAM from 1066Mhz to 800Mhz. If you had purchased 4 X 1024MB of PC6400 (800Mhz) DRAM, then you would have had to 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. A good analogy representing visualization of the above specifications is a passenger truck. Let‟s assume that the maximum hauling capacity of the truck is 8000 pounds representing 8GB of memory. The top speed of the truck is 106.6 mph representing a memory speed of DDR1066. However, this does not mean that the truck can haul 8000 pounds at 106.6mph. The physical limitations are similar for a memory controller as 8GB and 1066 are both tested maximums for this memory controller. When the memory controller speed is increased for overclocking, it simply cannot manage the same amount of memory at that overclocked speed for proper stable communication with the CPU. 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.

Read AN806 for more info, especially the portion about Overclocking on page 2.

When you set to 800MHz, you can then begin an overclock of the FSB which will in turn overclock the Northbridge/Memory Controller Hub (MCH) and which will concurrently raise the DRAM throughput. In this way, you can access the higher frequencies of the DRAM. The problem is NOT that the DRAM can not run at 1066Mhz. It is that the Northbridge/Memory Controller Hub can not access and load as fast with four banks filled as it can with two banks filled. This applies to the on motherboard Northbridge Memory Controller Hub (Intel) as well as the on CPU Memory Controller (AMD).

For example. You have the E6850 which has a default multiplier of 9X and a default FSB of 1333 (333 X 4 Quad Data Rate). Your DRAM is set to 800MHz (400 X 2 Double Data Rate).

Now if you raise your FSB from 1333 to 1400, you concurrently raise the Northbridge/MCH and the DRAM as well. Since you have the ratio of 1333:800 you can create a cross multiplication ratio (and by simple algebra) deduce what your DRAM will run at.

ie.

1333 is to 800 as 1400 is to X or:

So by simple cross multiplication you get the equation:

1333 * X = 1400 * 800 which via simplification brings you to 1333X = 1120000 or X = 112000/1333 which finalizes to X ~= 840

This gives you a CPU speed of 350 X 9 = 3.15GHz since FSB X Multiplier = CPU Speed.

Move the FSB to 1500Mhz and you gain a DRAM speed of ~900Mhz and a CPU speed of 375 X 9 = ~3.375Ghz.

Move the FSB to 1600Mhz and you gain a DRAM speed of ~960Mhz and a CPU speed of 400 X 9 ~= 3.6Ghz.

Now if you wish to drop your CPU Multiplier to 8, then you can go with moving your FSB to 1600Mhz, and you gain a DRAM speed of 960Mhz and a CPU speed of 400 X 8 ~= 3.2Ghz.

Move your FSB to 1750MHz and you gain a DRAM speed of ~1050Mhz and a CPU speed of 437 X 8 ~= 3.5Ghz.

So you see, this is DRAM created in the Quad setup for overclocking. You might not make the 3.5Ghz and 1050Mhz but be assured, you will gain a far higher clocking with these DRAM modules than you would with 800Mhz DRAM as that DRAM would not make these speeds.

If you were just looking for 4GB of DRAM and not overclocking then you would have been far better off to research and purchase 2 X 2048 6400C5DHX.

You will need to drop the speed of the DRAM from 1066Mhz to 800Mhz.

So, to refer back to my query, could I, assuming the memory copes, leave my CPU at 9x333 and set the memory multiplier to 3.00 (it's set to 2.4 at the mo) to try running it at 1000MHz. In your experience will easing it back 66MHz fix the problems? Would there really be any real life difference anyway? The other option (as you discussed) would be to increase to e.g 375x9 giving me a well overclocked CPU and 900MHz on the memory. Would this be the better option (again, assuming stability)?

If you were just looking for 4GB of DRAM and not overclocking then you would have been far better off to research and purchase 2 X 2048 6400C5DHX.

I did indeed look into this option but opted for the 4GB due to the higher spec. This is sold as a 4GB kit and is sold as memory to run at 1066MHz. What's the point if it doesn't??! It makes no sense. You might aswell say, "Pay more for this supposed 1066MHz 4GB kit even though it will only run at the same speed as a less expensive 4GB kit." Do you see what I'm saying.

Now, if I am able to run it at say 900 or 1000, I retract the above statement assuming that the 2x2GB 800MHz kit would not have a chance of running at 900 or 1000...or does it?

TDCat.

Hi,

I will check that when I get home.

What I can tell you is that my DDR voltage is set to 'Normal' on my mobo which states in the manual that it takes what it needs (not quite sure how that works...is it stated in SPD?). If I go the page listing the current voltages, it shows as 2.225V or thereabouts. Definitely 2.2xxV (not certain of the last 2 without looking).

Now, if I set the voltage manually and my BIOS lists the DDR voltage at...

DDR18V: 2.223V

Does this mean that standard for my board is 1.8V and I would therefore need to overclock by 0.3V or 0.4V depending on rev?

Just on a sidenote, I must say that some of the errors experienced when the memory is set too high are really quite odd. I would expect inability to boot, BSOD, freezes etc but I'm seeing reports of corrupt files, inability to access certain stuff, random exits out of Windows setup, pretty much anything actually. I suppose this is normal as the memory is such a key part of any system, right?

I'll post back tonight when I have that revision for you.

Thanks for your help so far guys. Stability is absolutely key to me. Overclocking is not my game but I thought it would do the stated 1066MHz.

Thanks,

TDCat.

OK, here's where I'm at.

I have come back and firstly taken a look at the memory. It is revision 1.2 so it would seem the BIOS is picking this up.

HOWEVER...I have now loaded up Everest to do some checks. In all areas, the DIMM voltage is showing as 1.89?? It doesn't mention the figure seen in the BIOS anywhere. In fact, I was worried that my manual BIOS setting were being completely ignored but that's not so. I have increased the ratio to 12:8 and now have the memory at 1000MHz at 5-5-5-15 without problems. This gives the results below.

Which is telling the truth? I asked previously if the default for the motherboard is likely to be 1.8V and if I therefore need to +0.4V on the voltage increase setting. Any clue?

Thanks,

TDCat.

Sorry to keep replying to my own post but I keep trying new things. It seems that my CPU was set a little undervolt by the MB so I have now manually set the DDR and CPU voltage to 2.2V and 1.35V respectively and both are showing as such in the Everest tester.

I decided to try a little more and have bumped my FSB to 350. I am now operating at...

350x9 = 3150MHz which has put the memory up to 1050MHz at 5-5-5-15 2T.

All seems fine. I have run the Everest stress test for 10 minutes and there are no problems. The improvements in the basic memory benchmarks are considerable. See the attached file below and compare to the last.

I'm happy!!! :biggrin:

TDCat.

Sorry to keep replying to my own post but I keep trying new things. It seems that my CPU was set a little undervolt by the MB so I have now manually set the DDR and CPU voltage to 2.2V and 1.35V respectively and both are showing as such in the Everest tester.

 

I decided to try a little more and have bumped my FSB to 350. I am now operating at...

 

350x9 = 3150MHz which has put the memory up to 1050MHz at 5-5-5-15 2T.

 

All seems fine. I have run the Everest stress test for 10 minutes and there are no problems. The improvements in the basic memory benchmarks are considerable. See the attached file below and compare to the last.

 

[ATTACH]2853[/ATTACH]

 

I'm happy!!! :biggrin:

 

TDCat.

There you go. You have answered your own questions and have done the necessary overclocking. This is how you learn. What I posted was basically informative and theoretical. It is up to you to test and tweak to find your own sweet spot and let's face it, when you do it yourself, you get a feeling that is far better than another person giving you the settings.

When you begin to feel more comfortable with the settings and if you have a better CPU cooler than the stock one, then you can move the CPU higher by lowering both the CPU and Memory multiplier and raising the CPU FSB. You can find 3.4Ghz easy with that CPU and ~1066Mhz on the DRAM. This will bring you closer to 8000MB/s Read...

People keep complaining that they can not reach 1066 with four DRAM banks filled but the problem is that they do not buy this DRAM with the knowledge of what someone has to do to reach those heights. I'm glad to see that you caught on easily and early. I will use this post as a reference for those others.

:)

Now, if I am able to run it at say 900 or 1000, I retract the above statement assuming that the 2x2GB 800MHz kit would not have a chance of running at 900 or 1000...or does it?

Not a chance. You would have to drop the 800Mhz to 667 and then do what you have just done with your DRAM. This is the reason for purchasing that 8500C5 of course. Those who buy it and do not know this are not aware and ignorant of the fact that they will have to drop bandwidth and upclock the CPU<-->MCH<-->DRAM stream. Yours is, of course, high end "Overclocking" DRAM. :P

I'm happy!!! :biggrin:

 

TDCat.

Then so are we! Good news man.