OC Issues with timings

[Ndi]

Hi, new here (waves).

I have this PC with a GA-X38T-DQ6, an E6850 and a 2G 2 DIMM kit from Corsair (1600C7DHX) - that being 1600 MHz, CL7, Dual Heat Exchange. The ones that look like they eat other DIMMs.

This is (was?) something of a home overclocker's dream, a good board, one of the best CPUs to ramp up and some RAM that has been tested by Corsair to OC to 1600C7 (SPD claims 1333-9-9-9-27).

What I did was I ramped up the CPU to 3.6 GHz (400x9) and left the RAM to 1333 (now 1600) and CL9 as per specs. It worked fine (after water cooling, case mods and such). Hurray for me, I said, CPU was at 1.325V, which is quite low considering I saw people using 1.5V, RAM was stock voltage and FSB was at +0.10 volts (damned BIOS has relative voltages).

Now, on to my issue. Corsair said on the package that RAM was tested and guaranteed to work at 1600MHz, 7-7-7-21, at 1.7 volts. TESTED. Well, I can't possibly tighten the timings. Any attempt to reduce them from 9-9-9-27 results in BSOD while booting.

If the CPU is stable at 3.6 (I am aware of testing requirements), and the RAM is guaranteed, why don't they work?

Corsair has a page where they did tests with my MB and my RAM and CPU exactly and they ramped up RAM to 1660, but the CPU was at 2800 (400x7), so they lowered the multiplier to get it to work. I haven't tried that yet, since I fail to see the advantage in lowering my CPU frequency by over 20% - I can't possibly gain that much from the tighter timings.

I am really new at OC (but not new at general PC knowledge) so could you please explain why I can't run RAM and CPU high? I am not aware of any link between RAM latency and CPU multiplier.

And if not, am I wrong in assuming I get more from a dual 3.6 GHz (or more - it feels like I could push still) than from a CL7 RAM?

[jmdixon85]

Your right in saying that the RAM latency and CPU multiplier arn't linked. Have you tried increasing the voltage of the RAM? Been reading up on your RAM and at overclockers.co.uk it states "Tested together at 1600MHz, Vdimm = 1.90V, at latency settings of 7-7-7-20". You should be safe upto 2.1volt. I'm using Corsair 2x2GB DDR2 XMS2 DHX @ 800mhz and there crap for overclocking. Lucky to get them to about 825mhz at CL5-5-5-18 @ 2.2v. My old 2x1GB OCZ platinum was better.

[jmdixon85]

Just thought I'd let you know that on overclockers.co.uk there are a couple of reviews saying that your RAM runs at 1840MHz at 8-7-7-22. Doesn't state what voltage there running at tho.

[Ndi]

1.9? 2.1? Aren't those DDR2 voltages?

I have DDR3 with a JEDEC nominal of 1.5 and the box saying in large bold "tested at 7-7-7-21 at 1.7V". I assumed that since the nominal would be 1.5, I set "DDR3 voltage" at +0.2".

I may have understood them running at 8-8-8-24 or somesuch, but any modification of timings result in resets. Am I wrong in assuming I can do something between 1600-9-9-924 and 1600-7-7-7-21? Is it possible that it does nothing in between and I should just clock them to CL7 and ramp up voltage?

Gigabyte Easytune reports RAM voltage at 1.7, but it's been known to err. E.G., when I set the CPU to 1.4, ET5 reported 1.425 and CPUZ said 1.375. I wish I could use a multimeter.

I couldn't find the articles on the UK site you linked but they do sell my RAM and they seem to ...

Wait, I have the DHX G, not the DHX, my DIMMS are rated 7-7-7-20 at 1.8 V. Well, I'll increase voltage on RAM to a +.30V, still, my question stands, is it possible that my RAM can't do in-between? As in, will not ramp over CL9 unless V >= 1.8?

[jmdixon85]

Well according to what ive read you should have no problems running at 1600mhz @ 7-7-7-20 timings. Thats at 1.8volts tho. I'm at a loss as to why you get resets if you modify your timings. I'm guessing your at 1333mhz RAM speed now? at 7-7-7-20 timings? Now if you changed your timings to anything like 9-9-9-24 your system should start. After all, your slowing your RAM down doing that. Anyway, I've got the datasheet from Corsair up infront of me now. What I would do is leave the timings at 9-9-9-24 for now and just increase your RAM voltage to 1.8v or slighty over and speed up the RAM to 1600mhz. If all is well then go back into the BIOS and change the timings to 7-7-7-20. Please let me know how you get on. Your RAM is "Officially" tested at these speeds so it's very odd if you can't get them to work???

[Ndi]

No, right now I run 1600 (FSB@400, sync), at 1.7V, timings 9-9-9-27. It works at 1600 just fine, it will not time any faster.

I will up the volts to 1.85 or 1.9 and then try to tighten timings later tonight. If all goes well I'll try lower voltages to keep them working cool and long.

[Ndi]

Hurray for me.

Apparently, it will not time any tighter until you ramp up the voltage. Once I made it +0.3V (1.8 - BIOS setup shows the voltage in red over 1.75!), it magically worked at 7-7-7-20 as per specs.

So there you have it, for future reference, Corsair TWIN 3 X 2048 - 1600 C7 DHX G will only go over (1333 or 1600) 9-9-9-24 once you ramp up to 1.8V, when it will go to 1600-7-7-7-20, as tested.

Thanks for the suggestions.

[jmdixon85]

Well glad you got it sorted. Sounds like your motherboard was just trying to scare you a little. Gave up on my RAM, just won't O/C!!! And thats at 2.3 volts!!!