First-Time Overclocker, problems with E6750 and DDR2-800 RAM

[Static EMP]

I'm new to overclocking (never tried it until the other night). Read through the clunk's, graysky, and wolfram beginner's guides and got a good idea of it. Mainly followed Clunk's, I was overclocking fine when it came to booting, temps, and stability tests, until I realized the system wasn't stable. There would be mouse jitters, small lags... and furthermore, there would be huge FPS drops in 3dmark.

Anyway, I am doing it on my 4-year-old build:
E6750
4x1GB G.SKILL DDR2-800 RAM F2-6400CL5D-2GBNQ (1.8-2.0V, 5-5-5-15)
Asus P5K-E WiFi AP mobo
EVGA GeForce 9800 GX2
COOLER MASTER Real Power Pro RS-750-ACAA-A1 750W Power Supply

Now this sounds like an entire noob question with a simple answer, but I have spent the last 2 hours googling and couldn't find one. I set my BIOS according to clunk's guide. I set my ram timings manually to 5-5-5-15 and ram voltage to 1.8. I set my FSBRAM to a 1:1 ratio, for mine that is 333:667.

Here is the problem: When I overclock my FSB up to to 399 MHz, (DRAM 799 Mhz), I can benchmark in 3DMark and the FPS remains high and the final score raises. But as soon as I bring the FSB up one more interval to 400 MHz (DRAM 801 MHz), the FPS drops severely in 3Dmark, and the final score is about cut in half. The CPU score raises, but the SM2.0 and SM3.0 scores severly drop. Also I notice some jittering in the mouse, or lagging while trying to scroll down fast in a browser... which, according to what I've read, sounds just like basic symptoms of an unstable overclock.

I had started initially overclocking it far higher, to around 3.6 GHz, with boots, temps, and 8 hours of stress testing OK. I thought I had achieved a very successful overclock, but it was the 3DMark FPS that clued me that something was wrong.

Things I have tried:
I thought maybe it was the PCI-E bandwidth messing with the graphics card, although CPU-Z never said 1x instead of 16x. I tried setting the bandwidth to 100 and that did not help. I then set it back to auto, and tried increasing the RAM voltage to 1.9V. Did not help.
Before bringing the clock back down a notch, I went ahead and ran Memtest with the 400:801 set. I ran it overnight (about 7 hours) and had no errors.

I've heard of people getting to 3.6 and above with an E6750... Do I just need faster RAM? I know people clock their RAM faster than it's rated all the time, so I don't see how 1 Mhz over is causing the 3dmark score to immediately cut in half.

More things I have tried:
I tried changing the strap to 400, which brought the RAM down to 800 MHz instead of 801. Still had the choppiness. I then set the strap back to auto, but this time adjusted the timings to 6-6-6-12 instead of 5-5-5-15 (rated).
So with the timings at CL6, went ahead and tried the 3Dmark benchmark again and it ran smoothly.

So now I figured lowering the timings would allow me to clock up the FSB, and in turn push the RAM clock above 800. I tried 420:841, and then ran the benchmark. Immediately I could see the huge performance drop, so I rebooted and tried pushing the RAM voltage to 1.9V, but that didn't help. Set it back to 1.8V, and brought the FSB down to 410:821, then 405:811, then 402:805, and finally 401:803. Every one of these had the same severely reduced performance in the benchmark.

I then set it back to 400:801 (while maintaining the CL6 timings), which worked earlier as I had mentioned... and oddly enough, I had the same poor performance issue on this run. I did not expect that at all, as it worked a couple of hours ago.

So to recap, with 5-5-5-15 or 6-6-6-18 timings, 399:799 runs the benchmark smoothly, and 400:801 or anything above cuts it in half.

I have no idea what is causing this!

I'm pretty sure I've covered everything in excruciating detail, but if I'm forgetting anything, please let me know. Thank you!

 

[Termie]

I'm new to overclocking (never tried it until the other night). Read through the clunk's, graysky, and wolfram beginner's guides and got a good idea of it. Mainly followed Clunk's, I was overclocking fine when it came to booting, temps, and stability tests, until I realized the system wasn't stable. There would be mouse jitters, small lags... and furthermore, there would be huge FPS drops in 3dmark.

Anyway, I am doing it on my 4-year-old build:
E6750
4x1GB G.SKILL DDR2-800 RAM F2-6400CL5D-2GBNQ (1.8-2.0V, 5-5-5-15)
Asus P5K-E WiFi AP mobo
EVGA GeForce 9800 GX2
COOLER MASTER Real Power Pro RS-750-ACAA-A1 750W Power Supply

Now this sounds like an entire noob question with a simple answer, but I have spent the last 2 hours googling and couldn't find one. I set my BIOS according to clunk's guide. I set my ram timings manually to 5-5-5-15 and ram voltage to 1.8. I set my FSBRAM to a 1:1 ratio, for mine that is 333:667.

Here is the problem: When I overclock my FSB up to to 399 MHz, (DRAM 799 Mhz), I can benchmark in 3DMark and the FPS remains high and the final score raises. But as soon as I bring the FSB up one more interval to 400 MHz (DRAM 801 MHz), the FPS drops severely in 3Dmark, and the final score is about cut in half. The CPU score raises, but the SM2.0 and SM3.0 scores severly drop. Also I notice some jittering in the mouse, or lagging while trying to scroll down fast in a browser... which, according to what I've read, sounds just like basic symptoms of an unstable overclock.

I had started initially overclocking it far higher, to around 3.6 GHz, with boots, temps, and 8 hours of stress testing OK. I thought I had achieved a very successful overclock, but it was the 3DMark FPS that clued me that something was wrong.

Things I have tried:
I thought maybe it was the PCI-E bandwidth messing with the graphics card, although CPU-Z never said 1x instead of 16x. I tried setting the bandwidth to 100 and that did not help. I then set it back to auto, and tried increasing the RAM voltage to 1.9V. Did not help.
Before bringing the clock back down a notch, I went ahead and ran Memtest with the 400:801 set. I ran it overnight (about 7 hours) and had no errors.

I've heard of people getting to 3.6 and above with an E6750... Do I just need faster RAM? I know people clock their RAM faster than it's rated all the time, so I don't see how 1 Mhz over is causing the 3dmark score to immediately cut in half.

More things I have tried:
I tried changing the strap to 400, which brought the RAM down to 800 MHz instead of 801. Still had the choppiness. I then set the strap back to auto, but this time adjusted the timings to 6-6-6-12 instead of 5-5-5-15 (rated).
So with the timings at CL6, went ahead and tried the 3Dmark benchmark again and it ran smoothly.

So now I figured lowering the timings would allow me to clock up the FSB, and in turn push the RAM clock above 800. I tried 420:841, and then ran the benchmark. Immediately I could see the huge performance drop, so I rebooted and tried pushing the RAM voltage to 1.9V, but that didn't help. Set it back to 1.8V, and brought the FSB down to 410:821, then 405:811, then 402:805, and finally 401:803. Every one of these had the same severely reduced performance in the benchmark.

I then set it back to 400:801 (while maintaining the CL6 timings), which worked earlier as I had mentioned... and oddly enough, I had the same poor performance issue on this run. I did not expect that at all, as it worked a couple of hours ago.

So to recap, with 5-5-5-15 or 6-6-6-18 timings, 399:799 runs the benchmark smoothly, and 400:801 or anything above cuts it in half.

I have no idea what is causing this!

I'm pretty sure I've covered everything in excruciating detail, but if I'm forgetting anything, please let me know. Thank you!

You probably have a memory issue - some combination of voltage/timings, etc., is throwing you off.

That being said, I think the problem may be something that you haven't thought about: your dual-GPU video card. VGAs interact with system memory in mysterious ways, and dual GPUs are even trickier. Given that your system is completely stable in all CPU-related tests, I'm pretty much convinced that you don't have an overclocking problem. You have a GPU/memory subsystem compatibility problem. If you can, test the system with a single-GPU card. If you don't see the sudden drop in 3DMark, then you have your answer.

If you don't have another card to test with, then I guess you should be happy with your CPU at 3.2 (you didn't mention it, but that's what I'm calculating your OC to be right now, which is actually fairly significant for that chip). You simply don't have the multiplier to easily push 3.6. That would require a 450 FSB, which is seriously high for a P5K pushing a 65nm CPU.

 

[Static EMP]

It's funny you say that, the thought popped in my head before you posted that it could be something to do with the 9800GX2. Dual GPUs are weird and maybe they don't play nice with overclocking. Anyway, I got a shitty 6570 I used for testing once layin around.

Haha, as if experimenting with voltages, timings, and frequencies wasn't enough, now I gotta go through the hassle of uninstalling the NVidia drivers and installing the pain in the ass Catalyst drivers ;-)

 

[sm625]

Can you double check that moving back down under the 400MHz barrier improves performance? You should the CPUID PC Wizard 2012 benchmarks and post the results at 399 and 400 fsb so we can see exactly what it is that is being effected. Its probably just your memory bandwidth being cut in half, but we should verify that.

 

[Static EMP]

Okay, did you want me to run the processor benchmarks or the global benchmarks? I did both and posted a screenshot.

Link to pic: http://twitpic.com/9evbjr

As you can see, only diminished performance on the CPU at 400 is the "Mandelbrot Parallelized." On the global benchmark, The Cache and Memory Performance, Memory Performance, and Video Performance drastically decrease. This is all with the 9800 GX2

 

[Static EMP]

This is really interesting. After posting the pics of those benchmarks earlier, I went ahead and swapped the 9800 gx2 for the 6570. I could get it up to 399:799, but as soon as I put it at 400:801, it wouldn't even post with that card. I would have to reset the CMOS or swap with the 9800GX2, which would post at that setting.

 

[Static EMP]

bump... any ideas?

 

[Denithor]

Do you have a lower RAM divider, so you can push the FSB higher without forcing the RAM over 800? RAM speed has little impact on most benchmarks and even less in real world apps, but if it's unstable it will definitely affect your experience. Most motherboards from that time would allow you to turn down RAM a lot so you could really push the CPU without breaking the RAM.

 

[Termie]

Set at 333 strap. (1:1 ratio), set memory at 5-5-5-12, 2.0v. Set FSB at 400.

By the way, I really don't understand your odd ratios. A 400 FSB means 800MHz, flat, not 801.

 

[Static EMP]

Do you have a lower RAM divider, so you can push the FSB higher without forcing the RAM over 800?

No, 667 is the lowest divider. The P35 mobos don't go below that, as they don't officially support DDR2-533.

By the way, I really don't understand your odd ratios. A 400 FSB means 800MHz, flat, not 801.

Yeah, I don't get that either. But when I leave the strap on Auto, it gives me those odd ratios. I set the strap to 400 once via someone on another forum's suggestion -- it didn't fix the issue; however, it did make the ratio even at 400:800.

 

[Denithor]

No, 667 is the lowest divider. The P35 mobos don't go below that, as they don't officially support DDR2-533.

Well, that truly sucks.

The only other thing to try is relax the memory timings even further and maybe bump the voltage a touch higher and see if the memory will OC at all.

 

[Static EMP]

I just figured out for sure it's not the RAM. I set the RAM divider to 800, and set the FSB back to stock speed of 333, making the RAM run at 889 (333:889). The performance issue does not happen. So the RAM can be overclocked. So this means the performance issue with the graphics card only happens when the FSB is clocked to 400 and above. FSB<399, no graphics issue. FSB>=400, graphics performance issues and jittery computer. Does that shed any light on the issue?

 

[Termie]

Honestly, it's probably just coincidence that it's at 400MHz. You're likely running into some other wall on another voltage setting besides vcore.

At this point, I'd probably just enjoy the computer. The difference between 3.2 and a hypothetical 3.6 (which I doubt you could hit reliably) is insignificant in the grand scheme of things. It's a five year old processor after all. Anything that will have trouble running at 3.2 will be about the same at 3.6.

What vcore are you running at, by the way?

 

[Static EMP]

Auto, which I think runs around 1.41 but I have to double check the exact # when I get home.

 

[Termie]

Auto, which I think runs around 1.41 but I have to double check the exact # when I get home.

If you really want to push past the roadblock you've hit, you'll need to work with manual voltages. Unfortunately, I really don't know what voltages you'll need to get your system steady, but auto usually won't work because of all the other voltage settings that come into play. This old thread might give you some ideas: http://forums.anandtech.com/showthread.php?t=2060388

Here are a few more:
http://forums.anandtech.com/showthread.php?t=129638
http://forums.anandtech.com/showthread.php?t=94955
http://forums.anandtech.com/showthread.php?t=110599

For the record, I had an e6600 that would run pretty solid at 3150 but couldn't quite stay stable at 3.2 on auto, and I don't think I ever bothered to try manually adjusting the voltages (it was my first home-built rig)...so the issue you're having doesn't surprise me too much.

 

[Static EMP]

Thanks for the links! I read through them all. The CPU probably is getting enough voltage at 1.4 then, I would think. I'll still try adjusting it manually. But does that make you think its probably more related to the NB voltage? The northbridge, after all, is what links the FSB with the PCI-E... right?

 

[Termie]

Thanks for the links! I read through them all. The CPU probably is getting enough voltage at 1.4 then, I would think. I'll still try adjusting it manually. But does that make you think its probably more related to the NB voltage? The northbridge, after all, is what links the FSB with the PCI-E... right?

Here's your answer on FSB: http://computer.howstuffworks.com/motherboard3.htm

As for your manual overclock, when you have the chance, go into your BIOS and list which voltages you can manually adjust. That will provide some ideas. One of the veteran overclockers in that first thread suggested upping northbridge voltage by 0.1v. Might not be labeled that way though.

 

[Static EMP]

CPU Voltage
CPU PLL Voltage
FSB Termination Voltage
DRAM Voltage
NB Voltage
SB Voltage
Clock Over-Charging Voltage
Load-Line Calibration
CPU GTL Voltage Reference
MB GTL Voltage Reference

 

[Termie]

CPU Voltage
CPU PLL Voltage
FSB Termination Voltage
DRAM Voltage
NB Voltage
SB Voltage
Clock Over-Charging Voltage
Load-Line Calibration
CPU GTL Voltage Reference
MB GTL Voltage Reference

In that case, try the NB voltage, starting with the smallest increment possible. Also set your CPU voltage (vcore) to something that gives you a good comfort zone - probably 1.35v judging from the old threads. It almost definitely can come down from there once you get stability. I'd also set your DRAM voltage at 2.0 for now. You might try adjusting the PLL voltage as well, but again, only by the minimum increment at first.

 

[Static EMP]

Will do when I get home and let you guys know. If it doesn't work, I'll also check lowering the multiplier but raising the FSB to above 400 to see if it's the FSB at 400 that's the wall, or the total clock speed.

Thanks again for being so helpful and patient.

 

[Termie]

Will do when I get home and let you guys know. If it doesn't work, I'll also check lowering the multiplier but raising the FSB to above 400 to see if it's the FSB at 400 that's the wall, or the total clock speed.

Thanks again for being so helpful and patient.

No worries. Lowering the multiplier and pushing the FSB will be interesting, but unfortunately, if that's the problem, you won't actually get much out of it. With a 7x multiplier, even a 450 FSB, which would be very high, would only net you 3.15, and you're over that already.

 

[Static EMP]

I got around the problem! Finally!

It was the NB voltage the whole time. I set it to 1.4V manually, and the 3Dmark graphics card ran smoothly. After that I raised the FSB pretty high, to about 450, and got a BSOD. I jumped so high because before I noticed the graphics problem, I was passing stress tests around 3.6 GHz. My guess is without the NB voltage manually set, it probably never was really reaching that level. Because with the NB voltage set, as soon as I got in the 430 range, I needed to manually set vcore, as auto stopped working for that setting as well.

Anyway, I got my system stable at 440 with vcore set to 1.4850 if I can remember correctly, as I woke up to an orthos stress test with no errors. CoreTemp's max was in the high 60s, while HWMonitor's was 70 for both cores and RealTemp's 71. They always read higher than CoreTemp (and if anyone knows which one to trust the most, feel free to chime in). Thanks for all your help and input; I'm excited to see how much performance I can squeeze out of this thing. Now I'm gonna have to deal with figuring out when it's the CPU voltage, CPU PLL voltage, FSB termination voltage, NB voltage, or even if the RAM voltage needs to get just a tenth over rated for really high speeds.

I'm assuming that not getting the graphics error as I continue to OC doesn't rule out that I need to increase the NB voltage levels though, right?

P.S.
It's funny, I had never been so happy to see a BSOD before. The graphics card problem was preventing me from pushing the chip to anything that required voltage tweaking (>400 FSB). So I hadn't gotten one BSOD since I started OCing this thing. They started to piss me off right away on my way to a stable 3.520 Ghz, though.

 

[Termie]

I got around the problem! Finally!
It was the NB voltage the whole time. I set it to 1.4V manually, and the 3Dmark graphics card ran smoothly. After that I raised the FSB pretty high, to about 450, and got a BSOD. I jumped so high because before I noticed the graphics problem, I was passing stress tests around 3.6 GHz. My guess is without the NB voltage manually set, it probably never was really reaching that level. Because with the NB voltage set, as soon as I got in the 430 range, I needed to manually set vcore, as auto stopped working for that setting as well.

Anyway, I got my system stable at 440 with vcore set to 1.4850 if I can remember correctly, as I woke up to an orthos stress test with no errors. CoreTemp's max was in the high 60s, while HWMonitor's was 70 for both cores and RealTemp's 71. They always read higher than CoreTemp (and if anyone knows which one to trust the most, feel free to chime in). Thanks for all your help and input; I'm excited to see how much performance I can squeeze out of this thing. Now I'm gonna have to deal with figuring out when it's the CPU voltage, CPU PLL voltage, FSB termination voltage, NB voltage, or even if the RAM voltage needs to get just a tenth over rated for really high speeds.

I'm assuming that not getting the graphics error as I continue to OC doesn't rule out that I need to increase the NB voltage levels though, right?

P.S.
It's funny, I had never been so happy to see a BSOD before. The graphics card problem was preventing me from pushing the chip to anything that required voltage tweaking (>400 FSB). So I hadn't gotten one BSOD since I started OCing this thing. They started to piss me off right away on my way to a stable 3.520 Ghz, though.

WOO-HOO!!!!!

I'm almost as excited as you are about this - it's always satisfying to figure out a problem even if it's not your own!

LOL at being happy about the BSOD, BTW!

On the temp front, I'd trust HWMonitor. And as for the NB voltage, you'll need to find the best setting for it by trial and error, but as you continue to push the clock speed, you'll probably need to continue to push the voltage. Watch your temps, including chipset temps, as you do this.