Mhz of DDR3

[ZixteE]

I just bought earlier another [HYPER X FURY DDR 3 4GB] 1866Mhz. So i have 2 sticks of  [HYPER X FURY DDR 3 4GB] 1866Mhz. Why does the Mhz shows 798Mhz on [CPU-Z] and to [Speccy] also. If that is the speed 798Mhz then it should be 1600 Mhz right?

 

 

[vorticalbox]

because of DDR aka double data rate. 

 

edit, misread enable xmp in your bios

 

 

[Jurrunio]

Read RAM speed in BIOS. That's guaranteed to be accurate

[mariushm]

Because the real frequency is 798 Mhz but for every Hz,the memory stick transfers 2 bits of information to the cpu

(DDR means double data rate) so to keep things simple, it's easier to just advertise the sticks with double the frequency

(so your stick runs at 798x2 = 1596hz)

The stick may work at 1866 Mhzif your motherboard supports it, but you may have to configure it manually in bios (the SPD tab should list the parameters for 1866 Mhz  ( ~ 933 real Mhz)

[ZixteE]

21 minutes ago, mariushm said:

The stick may work at 1866 Mhzif your motherboard supports it, but you may have to configure it manually in bios 

yes my motherboard supports it [Asus H61M-C] what will happen if i adjust the frequency of my ram?

[ZixteE]

23 minutes ago, mariushm said:

(DDR means double data rate) so to keep things simple, it's easier to just advertise the sticks with double the frequency

(so your stick runs at 798x2 = 1596hz)

but if you divide it by 2's 1866/2 = 933 Mhz right? my ram is not 1600Mhz its 1866Mhz

[ZixteE]

Just now, Strike105X said:

give us a screen of the SPD window in CPU-Z

 

[ZixteE]

So overall the default speed of my ram is 789Mhz if i want to change it i need to do it manually on bios right?

[ZixteE]

SO if i changed the Mhz will the voltage change too?

[mariushm]

11 hours ago, ZixteE said:

 

CPU-Z seems like it only shows the last 4 profiles stored in the memory stick.  The last one for your memory is JEDEC #8 888 Mhz (1776 Mhz) which is probably there for compatibility reasons because there's already a better profile JEDEC #6 which lists the same frequency but lower timings (888 Mhz 10-11-10-29-40)

 

So you know for sure the memory can do 1776 Mhz at 10-11-10-29-40 , and since it's sold as 1866 Mhz it will most likely be able to work at 1866 Mhz (933 Mhzx2) - it's not a big step up from the JEDED #6 profile. 

However since it looks like the memory stick does not have a profile for 1866 Mhz, you may have to go in BIOS and configure the frequency manually to 1866 Mhz and you may also have to adjust the timings because the ones currently set are for 1600 Mhz and at 1866 Mhz these may not work.

As the ram says it can do 10-11-10-29-40 at 1776 Mhz, it should be capable of working with these at 1866 since it's not a big step up but simply because I'd just want to get it workind and not worry about it,  i would start by slightly relaxing the memory timing to 11-11-11-29-40 - there wouldn't be much difference in real world use, you wouldn't feel a difference using these slightly slower timings.

I'd keep the voltage the same standard 1.5v .. if it can do 1776 Mhz at 1.5v it should do 1800 Mhz as well.

 

So basically, write down on a piece of paper 1866 Mhz and 11 , 11, 11, 29 , 40  and what each means (copy the column on the right)... then go in bios at memory and set those parameters to the proper values, save and reboot.

If you want to make sure the memory works OK , you can create a bootable USB disk or CD with memtest : http://www.memtest86.com/download.htm

You boot from it and will automatically run some tests on the memory (test runs for probably more than about 15 minutes and then loops so once it completes a full test you can just turn off your pc). 

If you have memory errors, you may want to raise the voltage to 1.55v from the standard 1.5v just in case the memory chips can't handle the higher frequency at the default voltage and run the test again.

If you still get errors, could be the motherboard just can't do 1866 Mhz with 2 x 8 GB memory sticks so you should just let it go and set it back to 1600 Mhz

 

[ZixteE]

very well said! thank you so much! it helps me alot