Tom's Hardware > Forum > Overclocking > General Discussions > FSB+1 = Some GB of ram disappears..what?

FSB+1 = Some GB of ram disappears..what?

Forum Overclocking : General Discussions - FSB+1 = Some GB of ram disappears..what?

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ottosen   09-05-2009 at 07:39:28 PM

Hi,

the topic kinda says it.

I'm currently running at 185 BCLOCK giving me 3.71 GHZ on my 920 core i7. This puts my ram at 1850 MHz approx, using 1.4125 QPI/DRAM voltage, and 1.75 DRAM voltage.

When I boot, the computer locates 12 GB of ram, but if I increase the BCLOCK to 186 or more for that matter, it suddenly only finds 8 GB of ram, and sometimes less, depending on the BCLOCK.

I've also tried increase the voltage on some of the above mentioned settings.

Another thing..if I set the management of voltages to auto, and go with 190 BCLOCK giving me 1902 MHz RAM, the hardware monitor says that my DRAM voltage is 1.9 - isn't that EXTREME?

However, going with this supposedly working (as it finds the 12 GB) isn't stable..when using prime95, some of the processes fail.

Any help?

Thanks :)

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spinny   09-06-2009 at 03:27:53 AM

Exactly what kind of memory is this? Is it rated to run at these speeds?

1.9v is too high. Intel claims that anything over 1.65v on memory for i7s runs the risk of damaging the CPU, so be wary when raising it.

Lastly, are you actually trying to overclock the memory, or just the CPU? IMO overclocking the memory past spec is pointless. If you are not trying to do this, just lower your memory multiplier.

Reply to spinny
cjl   09-06-2009 at 03:54:06 AM

The RAM isn't stable, so some of it simply isn't showing up. As for voltage, I'd be somewhat careful with RAM voltage - Intel has a rather strongly worded warning about running RAM over 1.65V on an i7. Try lowering the memory multiplier so you don't need to have your memory at such a high speed.

------------------------------ Asus P6T deluxe
i7 965 @ 4.2GHz (200*21), 1.384V
12GB Corsair Dominator DDR3-1600 CAS 7
 Reply to cjl
ottosen   09-06-2009 at 12:23:27 PM

Well I was trying to clock both really. I just find it really hard getting it stable when I OC the ram too.

The RAM's stock speed is 1600 MHz.

I'm not sure how much gain there is from OC'ing the different parts, but they all just seem to be so overclockable according to reviews and guides.

Reply to ottosen
cjl   09-06-2009 at 01:41:21 PM

The RAM gain is questionable - I'd lean towards keeping it at around the stock speed, rather than pushing the voltage that far. What timings are you using for the RAM? You could try relaxing them a bit...

------------------------------ Asus P6T deluxe
i7 965 @ 4.2GHz (200*21), 1.384V
12GB Corsair Dominator DDR3-1600 CAS 7
 Reply to cjl
ottosen   09-06-2009 at 02:03:07 PM

I was using 9 9 9 24. They come with CL7 timings at stock.

Basically this article was what made me wanna push them, as they're using the exact same RAM and showing a good increase in performance by running high hz at higher timings.

Reply to ottosen
cjl   09-06-2009 at 02:14:23 PM

Which article? All articles I've seen show negligible gain in most cases.

------------------------------ Asus P6T deluxe
i7 965 @ 4.2GHz (200*21), 1.384V
12GB Corsair Dominator DDR3-1600 CAS 7
 Reply to cjl
ottosen   09-06-2009 at 03:21:53 PM

http://www.hardwarecanucks.com/for [...] iew-6.html

This article.

I'm currently running at 4.1 GHz with the RAM doing 1563 MHz. The timings are 8-8-8-22, and it's stable. It just annoys me running less-than-stock speeds on the ram.

I just can't strike the right balance. If I pick a higher multiplier step for the RAM, it can't run at all. If I lower the FSB enough, the next step of the RAM could for example run at 1800ish MHz, but the CPU would be lowered a lot too. Even at 3.8 GHz and 1800 MHz on the RAM, I get errors during stress tests.

It's the RAM that poses the biggest problem in my OC'ing, clearly.

However, at 195 FSB, I can't go any further it seems. If I increase it to 200 (4.2 GHz), windows will crash pretty soon after.

It's a jungle :)

Reply to ottosen
spinny   09-06-2009 at 05:45:33 PM

Basically no one overclocks their RAM past spec for exactly the reasons you are experiencing. You get big headaches for tiny to no gain, plus the added bonus of risking your RAM (and in this case possibly your CPU too).

Reply to spinny
cjl   09-07-2009 at 10:03:41 AM

Honestly, that article shows a few percent gain, which isn't worth the headache and risk IMHO. You could try running 200*20 for 4GHz and allowing 1600MHz RAM. That should work, unless you're hitting a bclk wall.


Message edited by cjl on 09-07-2009 at 10:04:41 AM
------------------------------ Asus P6T deluxe
i7 965 @ 4.2GHz (200*21), 1.384V
12GB Corsair Dominator DDR3-1600 CAS 7
 Reply to cjl
ottosen   09-07-2009 at 11:23:14 AM

Funny thing you said that. It's exactly what I'm running right now. 4 GHz and 1600 MHz ram. I'm not sure what the wall would be..if I increase it, I do believe it crashes in windows.

With my current settings I stress tested using Prime Blend for 12 hours, and it was fine. I stopped it, but after a reboot windows froze during some browsing. Since then nothing has happened.

I'm running the RAM at 7-7-7-24, I'm not sure if that's what's causing it, but they're labelled at those speeds.

BClock wall is what?

I'm also OC'ing my gtx295 EVGA using their precision tools, but I seem to hit a wall at 690ish MHz (linked to shader clock) and around 1150 Memory clock. I'm not sure if that's good or not really.

Reply to ottosen
cjl   09-07-2009 at 12:23:03 PM

bclk wall would just be if the bclk was limiting your overclock instead of the core speed. Usually, at the bclk levels you're talking about, it's the CPU core that is limiting your overclock, so you can play around with bclk and mult a bit to get the memory where you want it (which is why, for example, my 4.2GHz overclock is actually below the default multiplier on my i7 - it refuses to run at really high multipliers, and 200bclk lets me run my RAM at 1600).

------------------------------ Asus P6T deluxe
i7 965 @ 4.2GHz (200*21), 1.384V
12GB Corsair Dominator DDR3-1600 CAS 7
 Reply to cjl
jitpublisher   09-07-2009 at 02:28:58 PM

Increasing memory speed is one of the least noticable real life speed improvements.
Benchmarks may look interesting and make you feel good about increasing memory speed, but you must have a really significant jump to get a difference you can actually see or feel.

Reply to jitpublisher
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