View Full Version : RAM Troubles

09-22-2009, 02:22 AM
I've recently bought the following items:

Motherboard: gigabyte GA-P55-UD3
CPU: Intel Core 2 i5 750
RAM: Corsair 2 x 4GB DDR3-1600 (TW3X4G1600C9DHX)

Now then, I've a feeling I've bought the wrong RAM for the job. Reading around, it seems that you're not supposed to use any RAM with a voltage higher than 1.6V. I think I remember seeing it recommended as low as 1.5V on Intel's website, but I can't find where I saw that anymore.
Intel's site even goes as far as not even listing DDR3-1600 at all ("Memory Types: DDR3-800/1066/1333").

Now I'm a bit confused. I'm hearing different things from different places. Will the i5 750 not take DDR-1600 RAM at all, regardless of voltage? Would it be possible to safely set the voltage lower? I'm just guessing here, as I know nothing about adjusting RAM settings.

To make things worse, I actually originally ordered the DDR3-1333 version of this RAM (TW3X4G1333C9DHX) but as it was out of stock, I was offered the one I'm stuck with now.

Basically I have these options, based off the little info I could find:

TW3X4G1333C9 | DDR3-1333 / PC3-10600 | ??? | Standard
TW3X4G1333C9A | DDR3-1333 / PC3-10600 | ??? | Added heat spreader
TW3X4G1333C9DHX | DDR3-1333 / PC3-10600 | 1.60V? | Bigger heatsink
TW3X4G1600C9DHX | DDR3-1600 / PC3-12800 | 1.80V? | Bigger heatsink

09-22-2009, 03:34 AM
Yeah seems like the voltage is too high for the job. It's probably meant for AM3 Phenom IIs...

Officially Lynnfield supports up to 1333, 1066 for Bloomfield. But 1600 should work, it's probably just the voltage.

Anyway I notice the specs sheet for your RAM (http://www.corsair.com/_datasheets/TW3X4G1600C9DHX.pdf) is dated April 2008, long before Nehalem debuted.


09-22-2009, 03:50 AM
Ok, I'm not sure about the differences between the different.. versions? (what's the proper word here?), Lynfield, Bloomfield etc, or how to tell which you have. I just know I ordered the Lynnfield.

So you say 1600 should work, but what about the voltage? If it's as high as it says it is, isn't that going to be a problem?

Note that I haven't actually done anything with the hardware yet. All sitting here ready to be used when I've got all this sorted out. Might end up having to return the RAM.

09-22-2009, 04:34 AM
You should have checked this list first: http://www.corsair.com/products/corei5/default.aspx


09-22-2009, 05:28 AM
I did, but like I said, the DDR3-1333 RAm that I had originally ordered was out of stock, so I was "upgraded" to the 1600.

I'm not sure on the differences between the TW3X4G1333C9 which is on the link above, and the TW3X4G1333C9DHX. Obviously the DHX has the extra heatsink cooling, but I don't know if the voltages etc. are different. There's not a whole lot of info on Corsair's website.

09-22-2009, 06:08 AM
I think you should return it for the one that wasn't in stock. I'm sorry about not being able to build it now despite having the stuff with you.


09-22-2009, 06:23 AM
I think that's what I'm going to try and do.

I'm just hoping that the DGX is identical to the non-DGX when it comes to voltages and whatever. If that is the case, there should be no problem. I wish they'd had made it a bit clearer.

T Rush
09-22-2009, 10:51 AM
ok so the deal is JEDEC (http://www.jedec.org/) decides the industry standards for how RAM should operate as a baseline...this is so every DDR3 RAM stick will fit in every DDR3 dimm slot, and run at a predefined voltage, at a recognized standard speed...the 'official' voltage that JEDEC describes DDR3 should run at is only 1.5v, and according to them the only speeds of DDR3 that officially exist are DDR3-800, 1066, 1333, and 1600 [wiki (http://en.wikipedia.org/wiki/DDR3_SDRAM#JEDEC_standard_modules)]
...but a RAM manufacture can 'rate'/sell RAM that runs at different speeds and voltages beyond what the official standard defines...however those RAMs must(should, some don't) still be able to operate at 'default' JEDEC standards so that they can work with any other parts(mobo and CPU) they might be used with...so the RAM will be programed with sets of micro codes that can be read by the motherboard BIOS so that initially 'safe' settings can be applied that will work with both the RAM and mobo/CPU...thus even if your RAM is 'rated' to run at 1.8v DDR3-1600, the BIOS and RAM micro codes("SPD timing tables (http://www.overclock.net/attachments/intel-memory/119524d1250125067-ddr3-1600-ram-showing-only-1066-ram-2.jpg)") should default it to run at 1.5v and one of the standard supported(by the RAM and mobo/cpu) speeds, like DDR3-1333 or DDR3-1066

in other words, you should be able to run your 1.8v DDR3-1600 rated RAM at default 1.5v DDR3-1333 speeds
...the high voltage is used with your RAM to get it rated to operate at 'quick' performing speeds/timings relationship...at lower speeds and voltages it will need to use more 'relaxed' clock cycle delay latency timings for that speed..likely this is how your RAM would run by default, automatically...and to achieve the highest rated speed(with the 'tight' rated timings for that speed) you would have to manually set the dimm voltage higher and apply settings(if the BIOS/CPU memory controller has the settings for lower divisors to run higher speeds) or overclock your platform to run the RAM at 800MHz DDR3-1600 speed

09-22-2009, 10:54 AM
This is a pretty decent statement of what can be run:

DRAM Voltage: As with the LGA1366 CPUs, a maximum 0.5V difference between CPU uncore voltage and memory is advised. Since there's no specific "uncore" voltage now (don't mistake CPU core voltage with the uncore that contains L3 cache, the memory controller and now PCI-Express controller), it does limit the extra voltage that can be applied to the memory and 1.65V is still the norm for most performance modules. We have run 1.8V for short periods of benchmarking to push our memory further, which the CPUs will handle fine, but we don't recommend long term use over the recommended settings.


Keep in mind that Corsair guarantees the RAM you purchased to run at the stated frequency and timings with 1.8V. Unfortunately, they don't say what it takes to run at lower frequencies and higher timings. I don't think you'll have an issue.

09-22-2009, 02:56 PM
Thanks you two - that's helped a lot.

So in theory, my DDR3-1600 should work without me having to tweak anything, and will essentialy be as if I had the DDR-1333 in there? And the DDR3-1333 is absolutely certain to work?

I'll try putting it all together when I get home tonight and see what happens! If it goes wrong, I should still be able to swap it for the DDR3-1333.

09-26-2009, 12:05 AM

I managed to put the pieces together today without blowing anything up. Connected my old hard drive and got into Windows fine. I'm now running Memtest86 to make sure the RAM is in order.

I took a look in the BIOS and it looks like the RAM has lowered itself to 1066 and 1.5V. I did try setting it to 1.6V, but it didn't seem to change anything. I don't knoow if I have to restart for it to take effect. I didn't really want to poke around too much. I've taken pictures of what's in the BIOS. Would be helpful if someone could give them a quick glance to check if everything's in order, and to let me know if I should touch those settings at all!

Main Screen (http://img3.imageshack.us/img3/5745/bios1s.jpg)
Status (http://img38.imageshack.us/img38/5664/bios2r.jpg)
Advanced Frequency Settings (http://img24.imageshack.us/img24/1871/bios3b.jpg)
Advanced Memory Settings (http://img21.imageshack.us/img21/7844/bios4.jpg)
Advanced Voltage Settings (http://img3.imageshack.us/img3/769/bios5s.jpg)

09-26-2009, 05:04 PM
The RAM made ~8 or so passes on Memtest with its default settings with no errors. So it seems to work at least. Now it's just those settings...

09-26-2009, 10:00 PM
Well, congrats on a successful i5 build :)


09-26-2009, 10:10 PM
Id try setting it to 1.65v and 1333 with maybe 8-8-8-21 timings.

09-26-2009, 10:27 PM
Ah, forgot to mention the timings.

As you see from the "screenshot", it's been set to 7 7 7 20. However, the RAM is supposed to be 9 9 9 24.

09-26-2009, 10:48 PM
Ah, forgot to mention the timings.

As you see from the "screenshot", it's been set to 7 7 7 20. However, the RAM is supposed to be 9 9 9 24.

Try upping the voltage to 1.65v and speed to 1333mhz, then run memtest again. If it doesnt pass try loosening the timings from there.

09-27-2009, 03:02 PM
I changed the voltage to 1.6 (forgot I was supposed to use 1.65!), the frequency to 1333 and the timings to 9 9 9 24. Or at least I think I did..
To get the frequency, I changed the "System Memory Multiplier" from Auto to x10. That got it up to 1333. I hope that's what I was supposed to do. The "x10" was a bit scary-looking.

I let Memtest run overnight and it got about 14 passes with no errors. I will try again tonight at 1.65V and see what happens.
I've also yet to test it in real-life, as I've got no games or applications installed at the moment.