RAM Speed Limited

[prince_xaine]

System Specifications:
Mainboard: Dell Optiplex 7010 MT 0GY6Y8
CPU: Intel Core i7-3770K
RAM: Corsair Vengeance Pro DDR3 1600 MHz 32 GB
GPU: Zotac NVidia GeForce GTX 1080 Ti
SSD: Samsung 850 Evo 500GB
SSD: KIngston A400 120GB
HDD: Western Digital Black 6 TB
HDD: Seagate Barracuda 500GB
PSU: EVGA 950W

Question:
So I have 1600 MHz DDR3 Memory installed, but it will not run at 1600 MHz, it runs at 1333 MHz. 1600 MHz is within the specifications of my Optiplex 7010 model. And because some people have stated that the computer is only meant to run 16 GB of memory, I tried running only 16 GB to see if this was the issue. Unfortunately, the computer still didn't run the RAM at 1600 MHz, no matter what configuration I tried. Any ideas? Thanks in advance.

Images:
Optiplex 7010 Bios: https://ibb.co/gu7ADK (yes it is the same as the 790 bios)

 

[william p]

That appears to be overclocked RAM running at 1.5V. and CL 9.
https://www.newegg.com/Product/Product.aspx?Item=N82E16820233538
The RAM that Crucial.com guarantees to run in that at 1600 is 1.35V. and CL 11-13
http://www.crucial.com/usa/en/scanview/D982439631D926C3
On an aftermarket overclockingMB you would turn up the Voltage, but that's not an option on a business computer like the Optiplex.

 

[prince_xaine]

I don't understand. The memory is listed as 1600 MHz, why wouldn't it run at that frequency? Why on earth would they sell it at an overclocked frequency?

 

[william p]

In overclocking turning up the Voltage allows thing to run faster. Back when DDR3 1333 was considered "fast" the only way to get DDR3 1600 was to overclock it. As time went by 1600 became a normal speed and the Voltage bump went away.
At 1.5V. CAS Latency 9 is still much faster then CAS Latency 11-13, so it's still a high performance part. But at 1.35V. apparently it can only do 1333.
It might run 1600 at CAS 11 1.35V., but it hasn't been set up to do that.

 

[prince_xaine]

Idk, I used a RAM software to check it out and it was at 1.5V if I remember correctly.

 

[prince_xaine]

https://ibb.co/cD1tJK

 

[william p]

if you take the speed in what you posted you will see that it's showing the timing for several differnt speeds. So that's mot what it's running. It's what it's programmed to run at various speed. You will notice that 666 speed and 800 speed both have 9-9-9-24 timings. That MB probably only can support 9-9-9-24 at 1333 speed. As shown at Crucial.com 11 CAS is what that computer supports at 800/1600 speed. The truth is CAS 9 @ 1333 is just about as fast as CAS 11 @ 1600.

 

[prince_xaine]

which is faster?

 

[william p]

CAS Latency is the number of cycles that a module needs to be idle to refresh the data. You will also notice a 2T at the bottom of the timings for 800 speed, this is another delay to help stability at the higher speed. The difference in latency is 22%, the difference in speed is about the same. The 2T @800 IDK but it doesn't help. My guess is they're just about equal for all intents and purposes.

 

[prince_xaine]

Ok thank you for the help. I actually learned a lot from this - I'm new to PC building - and I didn't know the difference in timings vs speed. So - the 1600 MHz sticks would be faster, but would have a slower response time = latency. Interesting. It appears they really just tried to push the DDR3 interface to its maximum capabilities, and were only able to do so at a cost of latency. So technically - they could push the speed and voltage higher, but again - the latency would increase as a drawback. I see now the appeal of DDR4. Thanks again for the answers!

 

[william p]

This was also true in the early days of DDR3. DDR2@800 was actually equal to DDR3 1066 in performance due to the higher latency. But as time went on latency got better, and speed increased and DDR3 became the way to go. The price situation reversed over time also. But a lot of people avoided DDR3 for a long time.

 

[prince_xaine]

I actually own a computer with DDR2@800. In all honesty, I don't really see a real difference between DDR2@800 and DDR3@1333. Would this be because I only use my computers for standard applications and gaming? If so, then is there really a point in worrying about the speed and latency of RAM in the begin with?

 

[william p]

There's really not much in it until you get into something like LGA1366 systems with 3 channel DDR3 memory. Then the 50% extra bandwidth and 6 core CPUs can really make an old system keep up. The thing is back when GPUs had 512K or 1GB RAM then it meant something. But with 4GB DDR5 and up GPUs system RAM is kind of on the sidelines now.

 

[prince_xaine]

Hmm. Makes sense. Thank you