Getting groovy with C7 2000 MHz memory on your AMD PC
Over the past year we've seen a shift in the memory industry, where the fastest DDR3 memory was a hot topic last year, these days it all seems to be about normal timed DDR3 memory yet with increased memory capacity. Inserting 4GB in a PC seems to be the norm these days.
Now that doesn't mean that there are several companies out there that will try and break records, to offer the fastest most enthusiast memory kits for suited platforms. Once Core i7 launched with the triple channel memory controller, things got out of hand, we went from 1066 MHz to 1333 MHz, to 1667 MHZ to 1866 MHz and then we even passed 2000 MHz. The latest record I heard that was broken was at 2500 something MHz I think.
It is all quite funky as when we go back to the PC era where the FSB rules the norm was 677 and 800 MHz DDR2 memory. As such memory has taken a huge shift in both capacity, frequency but also latency.
For AMD's products however there is very little memory available in the enthusiast segment. Really you need to look hard to find suitable memory that can take over ~1600 MHz and actually remain stable. As such G.Skill recently worked together with ASUS on some funky new 'FLARE' series memory.
These kits are optimized for AMD platforms preferably with the new six-core X6 processors, and in specific some ASUS motherboards. The kit we'll be testing today obviously comes from that series and is a 2,000MHz CL7-9-7-24 1.65V 4GB (2GBx2) DDR3 kit with its latest Flare heatsinks. Now to achieve 2000 MHz on the memory on an AMD platform is a challenge. Yet with supported XMP profiles in the BIOS you flick a switch and boom, the system configures itself for some really sweet low latency memory frequency and thus bandwidth.
The 2,000MHz CL7-9-7-24 1.65V 4GB (2GBx2) DDR3 kit are designed and optimized for the latest 6-core processors, that doesn't mean though your 'generic' X4 processor" won't work. No Sir. Have a peek at the coolness, and head on to the next page.
F3-16000CL7D-4GBFLS (2Gx2)
So the memory kit tested today come from that Flare series armed with PSC ICs, which relates (Flare) to the heat spreader design of the DIMM module.
| Main Board | AMD ( For Phenom II x6 only ) |
| System | Desktop |
| System Type | DDR3 |
| M/B Chipset | AMD 890 Series |
| CAS Latency | 7-9-7-24-2N |
| Capacity | 4GB(2GB x 2) |
| Speed | DDR3-2000 (PC3 16000) |
| Test Voltage | 1.65 Volts |
| PCB | |
| Registered/Unbuffered | Unbuffered |
| Error Checking | Non-ECC |
| Type | 240-pin DIMM |
| Warranty | Lifetime |
Judging from the specifications provided by G.Skill, they really do recommend this memory to be used with AMD's six core processors only, preferably in combo with one of the following motherboards:
- ASUS M4A89TD PRO
- ASUS M4A89GTD PRO
- ASUS M4A88TD-V EVO/USB3
The motherboards recommendation is there because G.Skill and ASUS worked really hard together to maximize the utmost stability and a user friendly experience. Now that doesn't mean that this memory won't work at other motherboards, contrary, we gave it a try and if you manually tweak the BIOS settings yourself you can achieve advertised frequency and performance quite easily.
Why then is one of the above motherboards so much recommended ? Well, we wanted to figure that out for ourselves and asked ASUS to ship in a M4A88TD-V EVO/USB3 (which we'll be using for this review). We flashed the latest BIOS in there and from there on, it's all easy. Simplicity at it's best. In the BIOS you go towards the Ai Tweakers section, hit CPU overclocking and select D.O.C.P. (D.O.C.P. relates to memory overclocking via the baseclock frequency).
Once D.O.C.P. is selected, then one tab below it you'll find the option DRAM O.C. profile, you select profile #1, save and boot into Windows with your memory completely configured at 2000 MHZ CAS 7 1.65V. The way it works is that the baseclock is increased a little to 250 MHz, your multiplier will run at 13 and then the profile tweaks everything that needs to be tweaked including voltages.
Overclocking memory to 2000 MHz CAS7 has never been this easy really ... this literally is 3 seconds work. Seriously, for AMD platforms it's one of the few memory kits we have seen we consider to be extremely uber cool.
G.Skill likely produced a limited number of these kits, but look around and you will find them in the stores.
The Flare kit is US$ 179.99 on newegg.com, in for example Germany it is 177 Euro. But head on over to the next page where we'll startup a product photo-shoot after which this article will dive into a benchmark session. Hey, we know you like it !
Product Gallery
Packaging ... hey we show you everything my man, we always start off with packaging so you know what to look for in the stores -- it's as simple as that really. And yes .. that might now be the final packaging. Hey we just care what's on the inside right. As you can see this kit comes with G.Skill’s a memory fan and installation guide.
Here we have the DIMMs after unpacking. This is the 4GB 2000 MHz kit = PC3 16000 with 2x 2GB DIMMs. Overall a nice design, wish that the PCB would have been black though. The heat spreaders are made out of aluminum for optimal heat conductivity. This kit can manage latencies of 7-9-7-24 at 1.65 Volts, and that is pretty impressive stuff alright! Labels is a Command rate 2T but we noticed they also run at a command rate of 1T at that frequency.
Very simple stuff, but the details of the modules can be read from a small sticker. You can spot the SKU code and generic info on there. Also primary info like latencies are displayed. It's good to see voltages being reported on there as well. A lot of memory producers lack this info, yet it is so important. Missing on the sticker is the command rate though.
With expensive memory often come a some extra's. G.Skill offers a life-time warranty with these memory modules, you can't beat that. Look at the heat spreaders, it's fairly unusual to see a design like that. One thing is a sure fact, you either like or hate the aesthetics. The green PCB bothers me a little though. Styling wise that's a missed opportunity.
The heatspreader is designed to enhance heat dissipation allowing better tweaks and overclocks. As a result this is not low profile memory though. The idea is that heat is moved away from the actual memory chips and this increases potential overclocking and stability. And in combo with the Turbulence memory fan the results could be wicked.
The kits will be sold with a G.Skill’s memory fan to decrease the system temperatures and provide further overclocking headroom during tweaking. The fan is quite silent, but the extra tweak potential always will be a little relative. We assume that if you build a PC with such high-end components, your chassis airflow would not be an issue either. It's definitely a nice stylish item that will look great in any PC.
One note to G.Skill, the compatible ASUS M4A89TD PRO, ASUS M4A89GTD PRO and ASUS M4A88TD-V EVO/USB3 motherboards are all blue/white themed. How nice would it have been to have matched the DIMMs in the same colors ?
Memory timings explained
What are memory timings?
Let's explain a little what you will run into with memory timings. First off latency. We used the word numerous times already in this article. Latency is the time between when a request is made and the request is answered. I.E, if you are in a restaurant for a meal, the latency would be the time between when you ordered your meal to the time you received it. The faster your order is served, the better right ?
Therefore, in memory terms, it is the total time required before data (your meal) can be written to or read from the memory. latency - lower is better.
Say we notice on the packaging is this: CL7-9-7-24 1.65V (2T) for a memory kit. What do the numbers mean ? Well this refers to CAS-tRCD-tRP-tRAS CMD (respectively) and these values are measured in clock cycles.
CAS Latency
Undoubtedly, one of the most essential timings is that of the CAS Latency and is also the one most people can actually understand. Since data is often accessed sequentially (same row), the CPU only needs to select the next column in the row to get the next piece of data. In other words, CAS Latency is the delay between the CAS signal and the availability of valid data on the data pins (DQ). Therefore, the latency between column accesses (CAS), plays an important role in the performance of the memory. The lower the latency, the better the performance. However, the memory modules must be capable of supporting low latency settings.
tRCD
There is a delay from when a row is activated to when the cell (or column) is activated via the CAS signal and data can be written to or read from a memory cell. This delay is called tRCD. When memory is accessed sequentially, the row is already active and tRCD will not have much impact. However, if memory is not accessed in a linear fashion, the current active row must be deactivated and then a new row selected/activated. It is this example where low tRCD's can improve performance. However, like any other memory timing, putting this too low for the module can result in instability.
tRP
tRP is the time required to terminate one one Row access and begin the next row access. Another way to look at this it that tRP is the delay required between deactivating the current row and selecting the next row. Therefore, in conjunction with tRCD, the time required (or clock cycles required) to switch banks (or rows) and select the next cell for either reading, writing or refreshing is a combination of tRP and tRCD.
tRAS
Memory architecture is like a spreadsheet with row upon row and column upon column with each row being 1 bank. In order for the CPU to access memory, it must first determine which Row or Bank in the memory that is to be accessed and activate that row via the RAS signal. Once activated, the row can be accessed over and over until the data is exhausted. This is why tRAS has little effect on overall system performance but could impact system stability if set incorrectly.
Command Rate
The Command Rate is the time needed between the chip select signal and the when commands can be issued to the RAM module IC. Typically, these are either 1 clock or 2.
Memory testing is a process of trial and error, find and seek the maximum. This is pretty much a sucker for your free time.
Traditional system: If you are going to overclock then increase the FSB, change the memory timings, but most of all alter memory dividers until your system won't boot. If you are not comfortable with such a thing, hey this isn't your game then. I recommend you to lower the processor's multiplier and then slightly increase the FSB with high memory timings and take it from there timings wise. For a Core i5/i7 system: change memory multipliers/dividers in the BIOS or overclock Baseclock, QPI frequency and memory voltage.
Going for 4 GB? Then go with a 64-bit operating system please
Windows 98, who didn't use that OS? What amount of memory did your PC have? Right, likely 128 MB. We now test a system that has 48 times more memory.
Over the years we progressed and noticed that applications have gotten more and more memory intensive. With Windows XP we moved towards 512 MB as standard to prevent the OS from swapping to the HDD, and as explained on the previous page with the latest games we see that the certain games really like 1 GB. All this has happened over just a couple of years.
When Microsoft launched Windows Vista, the biggest memory hog in the world. 1 GB was just be bare minimum recommended specification. They actually recommend 2 GB. And then there's 64-bit platforms supporting more than 4 GB memory. Now with Core i7 and it's triple channel memory controller, we tend to purchase 3x 2GB memory modules.
You use Vista 32-bit. I see 3 GB, where's my 4 Gigabytes of RAM?
Can you use 4, 6 or more GB of memory? Yes and no. As far as Windows 32-bit operating systems are concerned, the world ends at 4,096 megabytes. That's it. As an example I'll use a 4GB kit here. Say you get 4GB, it will run just fine, yet with for example Windows Vista 32-bit your memory size will be limited and you'll only have 2.9~3.2 GB out of the 4 GB available to you.
To address 4GB of memory you need 32 bits out of the address bus. There however is a problem - actually a similar problem that IBM faced when designing the original PC. You tend to want to have more than just memory in a computer - you need things like graphics cards and hard disks to be accessible to the computer in order for it to be able to use them. Microsoft call this MMIO (Memory-Mapped I/O).
If you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system.
So just as the original PC had to carve up the 8086's 1MB addressing range into memory (640K) and 'other' (384K), the same problem exists today if you want to fit memory and devices into a 32-bit address range: not all of the available 4GB of address space can be given over to memory.
For a long time this wasn't a problem, because there was a whole 4GB of address space, so devices typically lurk up in the top 1GB of physical address space, leaving the bottom 3GB for memory. And 3GB should be enough for anyone, right?
So what actually happens if you go out and buy 4GB of memory for your PC? Well, it's just like the DOS days - there's a hole in your memory map for the IO. (Now it's only 25% of the total address space, but it's still a big hole.)
So the bottom 3GB of your memory will be available, but there's a discrepancy with that last GB. If you want it all, go with a 64-bit OS. In 64-bit Windows, the limit is gone.
Anyway, let's throw the modules in some tests.
G.Skill DDR3-2000 C7 Flare with a Phenom II X6 1090T processor
Okay let's fire up CPU-Z so you can check out a little how we have the system configured.
So in the BIOS we can just flick on the XMP profile (see below) and at default we'll have the memory running at 2000 MHz CAS 7, surprisingly enough it ran 1T without any issues. Our motherboard reads the memory profile and applies optimal settings accordingly, including voltage set at 1.65V.
Do you see that XMP-2000 profile? If you have a decent motherboard or at least the one of the ASUS M4A89TD PRO, ASUS M4A89GTD PRO or ASUS M4A88TD-V EVO/USB3 motherboards, in the BIOS you will be allowed to to load up and apply that profile in the BIOS.
- Upside: your memory runs pre-configured at 2000 MHz C7
- Downside -- your system will start to get overclocked a bit as the profile requires the baseclock to be run higher.
So there's no way of running this memory at 2000 MHz with a default clocked processor (200 MHz base clock) -- make no mistake, overclocking is a requirement.
By having this as fixed option -- we can now run tests in-between standard 1333 MHz and 2000 MHz quite reliable with that processor fixed at 3250 MHz.
Once you applied the tweak you are good to go.
So here we have the memory screaming at 2000 MHz. And yes this is CAS 7 and a command rate of T1 -- the VDIMM voltage is set towards 1.65v at this stage. We ran a full sequence of Prime95 here which finished without any problems. Prime95 is both CPU and Memory dependant, any errors as a result of overclocking or bad memory and one of the worker threads would go red and result in an error. So we established that 2000 MHz CAS7 1T is absolutely flawless stable.
Here you can see the memory clocked at 2000 MHz CAS 7 yet now you can spot the read performance. We'll look into all numbers in the next pages where we'll address memory performance both synthetic and real-world. Now it's not exactly Core i7 bandwidth, but for an AMD setup this is pretty nice performance alright.
Let's have a look at some charts and games.
Refer To : http://www.guru3d.com/
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