It's that time again I recently purchased a Q6600, and apparently it's very very good @ overclocking.

My temps are way lower than my old E6400 even before any overclocking - I have therefor been experimenting with (much more successful) overclocking - however, there are some things that are puzzling me:

1. POST screen tell me I have 3GB (Which I do), but Windows (My Computer properties) and Task Manager tells me I have 2GB. CPU-Z tells me I have 3GB but still, Photoshop (in preferences) tells me I have 2GB (well, It doesn't tell per say, but I can see that it's not recognizing the remaining 1GB).

Whats up with that?! How much do I actually have, or how do I make sure I have all 3GB?


2. How exactly does RAM overclocking work (and when do I need to up the voltage)? Because of my CPU overclock, the DRAM FSB is lower, and POST therefore thinks I'm running PC2-4200 mem. But when doing mem speed tests, I can see that they are performing very well.

3. I tried clocking the CPU to 3.8GHz, and it went somewhat OK. I ran LFS for few mins and did a benchmark. The result was shocking.

I would get an average of 77FPS in one particular replay @ 3.5GHz, but got 44FPS when clocked to 3.8GHz.. huh?!

I later tried to do a FPU benchmark in Everest, but then the computer crashed (I'm pretty sure it was because I didn't supply it with enough voltage - had it set to 1.5v).


Why did I get lower FPS? That doesn't really make sense to me. The temperature wasn't an issue, as cores were at 45-46c while running LFS.

basically...the RAM should be at a 1:1 Ratio with the FSB...as your RAM is DDR2...example

380FSB should be at 760 Mhz on the RAM

But i'm not sure, what sticks do you have as your 3 Gb of RAM...3 1Gbs?

I'm not really sure how that works.

By the way, what cooler you using for your CPU

Quote from harjun :

basically...the RAM should be at a 1:1 Ratio with the FSB...as your RAM is DDR2...example

380FSB should be at 760 Mhz on the RAM

But i'm not sure, what sticks do you have as your 3 Gb of RAM...3 1Gbs?

I'm not really sure how that works.

By the way, what cooler you using for your CPU

No it shouldn't, its a good ratio to use but generally you get better performance by having the FSB : DRAM ratio weighted towards the FSB. Ie; 4:3.


Try switching the RAM position around, figure out which 2 are being recognised and swap one of those sticks for the one that isn't, see if its the actual stick. If it works fine, then try mixing and matching the slots until it recognises.

i've heard Windows XP only recognizes like....2Gb or something ofRAM

Quote from harjun :

i've heard Windows XP only recognizes like....2Gb or something ofRAM

LOL, no. XP can use upto 4 IIRC. Shouldn't have any problem with the XP side of things, sounds like hardware.

Thanks for the replies.

I'm on 3x1GB Corsair XM2 PC28500 Dominator thingies. I have another 1GB module on the side (they were bought in pairs).

I'll actually swap the 3rd one out with the one thats laying on my desk, to see how that goes.

I'm on a Scythe Infinity cooler.

Ps. Win XP 32bit doesn't recognize 4GB - maxes out at 3GB. However, I can't even get to POST with all 4GB inserted. I do suspect that a pair, or a single module is at fault here - I've read allot about these Corsair Dominatiors being a bit... faulty, even if a mem test doesn't show it.

Yeah, if you cannot post, its definitely a hardware problem, be it either a bad stick, or a faulty DIMM slot.

I think I'm getting somewhere now - so far I've been suspecting a module or two not working properly.

I did a test - had some RAM errors. Then turned off computer and placed the module into another slot. Another test and no problems (need to have the test run for longer though).

Whats odd is that at some frequencies, the RAM would function well while at others, it just wouldn't.

For instance - I would get BSOD problems if I picked almost anything else beside the lowest DRAM freq. in BIOS.

I'll let it run the test for a while before I get into further tweaking and OCing - still wan't more juice out of the CPU :P I think 3.8GHz might be more realistic, now that I know a bit better about the RAM problem

Just an obvious thought, but when you change the RAM frequencies, you are setting the correct voltages right? Like 1.9 or 2.1V or whatever the RAM runs at.

Not really - I decided to stop bother with it and leave it at 1:1 and use the specified 2.2v - but can only set 2.15 or 2.25, so I went with 2.15.

1. In 32bit versions of Windows, even though the theoretical limit of RAM is 4GB, any one application can only recognize 2GB because the other 2GB is reserved for the kernel/system. You can change IF YOU REALLY WANT TO by following the directions here. This really isn't such a great idea though, because you're restricting how much RAM the kernel can use. Also you need to put in the last stick since you don't want all 3GB reserved for your applications.

What video card do you have, and how much VRAM does it have? I ask this because you have to take this into account because the 4GB limitation of 32bit operating systems includes your VRAM (and a few other pci bus things), so if you have a card with 512MB of memory and you're reserving 3GB for your applications, that's LESS than 512MB of RAM for the kernel.

In short, put the other stick of RAM in, don't mess with the boot.ini thing, and don't ever worry about it.


2. RAM is overclocked with the Front Side Bus (FSB, or bus). You also have to take into account the RAM divider (CPU-Z will tell you, and you can find/change it in the BIOS).


3. It's likely getting too hot and throttling down. It'll throttle to a 6x multi, so instead of 9*422MHz = 3798MHz it's 6*422MHz = 2532MHz. And well... you can understand why 2.5GHz would give lower results than 3.5GHz I suspect. However I can't really be 100% certain that this is what's causing it since I'm not there with the system.


Have you tried running each stick of RAM by itself? Have you run Prime95 to check stability? You can get a version that supports 4 cores here. Since you seem to be having RAM issues you should probably chose the setting that says "Tests RAM" (it'll be obvious once you start the program). I suspect you'll error out pretty quickly with whatever stick is giving you issues, but I'd run each stick by itself (then the 3 good sticks) for at least a few hours to ensure stability.

Of course, you were at 3.8GHz when you BSOD'd, so it could be that under load (and given that it may have been throttling in LFS), I'd run that test in SP2004/Prime95.

Thanks for the extensive reply.

1. I've actually been using the /3GB switch and doing some very memory extensive Photoshop Work, but havnen't noticed any issue so far - however, I can't do the work without the /3GB switch (unless I wasn't Windows to swap.. and I really don't want that).

My last work (place) was with lots of video editing and post production, where I also used the switch to get more mem for the apps (PC had 4GB installed though).

What type of problem(s) would I get if the kernel doesn't have enough memory?

I have a Nvidia 8800GTS 640MB - this would mean that kernal only have 360MB? Again, I haven't noticed issues.. but maybe I'm not looking for the rights things/signs?

As mentioned, I can't use the last ram module, as the computer wont start at all (no POST screen). Recent test points towards a faulty mem slot - I'll do more tests when I get the chance.

2. Yah, thats what I figured too, but wasn't sure.

3. I highly suspect it was because I used a saved OC profile in BIOS as base, that didn't have thottling features turned off. I clocked it to 3.8GHz again last night, and reached much much better results.

Heat wasn't that much of an issue, as ambient isn't high, and CPU is cool enough to stay within core temp limit. I was pushing it though - I turned it back down, because I know that I'll get problems once we get into the warmer seasons.

I haven't tested the modules individually, but I will give it a shot to make sure whether or not it's an module or the slot, being the cause of some of the problems.

I use Prime95 all the time, however I use Memtest for mem testing.

Ps. I've had plenty of BSOD's, not just @ 3.8GHz - I'm using Core temp (it crashes all the time), Speedfan (with +15c offset) and Everest to monitor temperatures - and even though I some times have been pushing the CPU pretty hard, by far most (if not all IMO)of the BSOD's werent caused by temperature.

I switched one module to a free slot (never used it before), and havn't had BSOD's since.