E6520 Owner's Thread

Hmm 2133 sounds too high for the low voltage laptop memory runs at. I think I'll just go for 1866.

 

I tried to flash 1 stick to 2133MHz cl=12, and bios shows the memory really running at 2133MHz. But it's very unstable, bsod happened when windows boot.

Then I plugged in the other stick and flash back to 1866MHz.

The conclusion is E6520 can support both ddr3-1866 and ddr3-2133, but my samsung stick cannot run at 2133MHz.

 

Guys, why in the world would you try to overclock memory with a higher CAS? Are you just interested in seeing the highest number? In reality, these mobile processors being discussed will not go above 1600MHz no matter what the utilities are telling you about the memory. All you are doing is stressing the components and making the latency higher, which is counter productive.

Many people do not realize the CAS being lower is more improtant than the bus speed. 1333MHz CL6 or CL7 memory will always beat out the 1600 or 1866MHz CL11 or CL12 since the lower CAS in this example can handle almost twice as much data in the same amount of clock cycles. So in the end, you may have what appears to be faster memory with the higher bus speed (thanks to good marketing by the memory companies), but the processor will not handle it any faster and the -5% to +3% difference in data transfer does not justify the risk to the hardware and voiding the warranty.

This is just my opinion.

Scott-

 

The higher the memory frequency, the higher the bandwidth. 800mhz CAS 5 will have the same latency as 1600mhz CAS 10, but the 1600mhz ram will have 2x the bandwidth and provide significantly better overall performance. There is no false marketing, just that some applications may have low bandwidth requirements, making latency the only real factor in performance.

I plan on using the eGPU at home, but when I use the laptop somewhere else I'm going to have to depend on the HD 3000, which uses the system memory. All video cards care about is bandwidth, not latency. Look up graphics card memory latencies, they are ridiculously high (CAS 20+) to get as much bandwidth as possible. Outside the HD3000 performance though, benchmarks have shown that higher performance memory doesn't do a whole lot for system performance.

Thanks futchi for risking your memory to learn what the e6520 can handle. It was interesting for sure.

 

Video, especially 3D, relies on speed, not so much bandwidth after a cerain point.

Yes, the latency in time is the CAS latency divided by the clock frequency. Therefore, the following are the important numbers to consider regardless of bandwidth since you're limited to the bandwidth of the processor, not the memory:

CL7 cycles @ 1066MHz/sec = .0066 x 10 = 6.60 nanoseconds

CL7 cycles @ 1333MHz/sec = .0053 x 10 = 5.30 nanoseconds

CL9 cycles @ 1333MHz/sec = .00675 x 10 = 6.75 nanoseconds

CL9 cycles @ 1600MHz/sec = .0056 x 10 = 5.60 nanoseconds

CL11 cycles @ 1600MHz/sec = .0069 x 10 = 6.90 nanoseconds

CL11 cycles @ 1866MHz/sec = .0059 x 10 = 5.90 nanoseconds

CL12 cycles @ 1866MHz/sec = .0064 x 10 = 6.40 nanoseconds

CL12 cycles @ 2133MHz/sec = .0056 x 10 = 5.60 nanoseconds

Can you see the pattern here? This is what I mean in regards to marketing. Regardless of CAS and bandwidth, all these sticks are pretty level across the board when it comes to real world throughput. In regards to the i7 2720QM, I would much rather run CL7 1333MHz than CL11 1600MHz for the obvious reasons above since the latency speed bump would outweigh the small bandwidth improvement on the higher freq. memory. To see a small but noticeable difference while peaking the i7 2720QM 1600MHz FSB, one would need to find some CL8 1600MHz (5.0ns) memory, but the cost would not be cheap. In the end, we are still talking about 3~5% performance differences so it means nothing at this stage unless you simply want to show your friends some high clock numbers.

Scott

 

The specifications in intel website show 2720qm only supports 1600MHz or lower, and i7-2620m and i7-2600 support 1333MHz or lower.

But in desktop p67 platform, one can use memory higher than specification by changing memory ratios. Now we find that qm67 (hm67 also reported) platform can also use memory higher than specifications, and the bios of E6520 will automatically change the memory ratios to support 1866 and 2133 memory.

 

Is the Kingston HyperX RAM 1866 compatible with the e6520?

 

Okay, so I'm a retard and can't figure out how to disable the onboard graphics and have the NVS4200 on instead. Any help?

 

Yes, one of the comments of hyperx 1866 in newegg mentioned it is OK for e6520.

 

Go into the BIOS and disable OPTIMUS from the VIDEO screen.