Building a Varnish-Cache Box at 2000MHz

I am building a box for a Varnish-Cache. The box must have ultra quick RAM, as the cache data are stored their. My limited component list thus far consists of 8GB 2000MHz 9-9-9-27 RAM; am I correct in assuming that a native motherboard capable of running the RAM without over-clocking is not possible? Specifically, I am looking at this MB (http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=618858&srkey=B450-2511) and this RAM (http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=6688692&srkey=C13-1009). With a CAS Latency of 9 at 2000MHz, I am looking at 0.0000045 cycles/sec.

Any other requirements? Assuming all you need is fast RAM, don't need much GPU or CPU horsepower, I'd go for this:

The memory you linked to is DDR3-2000 9-10-9-27 @ 1.65V. Intel recommends running memory on Sandy Bridge at 1.6V or below, but nobody has found adverse effects of running at 1.65V

However, this set is DDR3-2133 10-10-10-28 @ 1.5V. What you should be able to do is up the voltage to 1.6V or 1.65V, drop the speed down to 2000MHz, and possibly hit CAS8. Or keep it at 2133MHz and try to hit CAS9.

Thanks for the response Knufire. I have linked my complete component list. You are correct that Varnish does not require much of a CPU. I was first looking at using a Dual Core pentium with DDR2-800, but the 2000MHz offers better performance. Either way, it seems like I'll need to slightly overclock to get the RAM where I want it. The CPU should be just fine with the added voltage, as it will be running Ubuntu Server 10.04.3 without a load. My current Varnish usually operates at around 0.5-2 percent load. It is super light.

I think you're mistaken. On Sandy Bridge, everything is run off a single base clock. This base clock is also tied to PCIe frequency, which REALLY doesn't like being changed. For all intents and purposes, the base clocked is locked, and all overclocking is dependent on multipliers. You can overclock the CPU (if it's unlocked) while having zero effect on the RAM, and you can overclock the RAM with zero effect on the CPU.

You might want to consider the AMD APUs in this case. You would want someone else to confirm that they can handle 2000MHz+.

The A series can support 2000+ memory but it likes extra voltage to do it and the chips are a little picky about ram. I tried running mine with a set of ripjaws-x 1866 and regardless of what speed I set it to I would get BSODs. Changed it out for some different memory and now its running fantastic.

Knufire said:

I think you're mistaken. On Sandy Bridge, everything is run off a single base clock. This base clock is also tied to PCIe frequency, which REALLY doesn't like being changed. For all intents and purposes, the base clocked is locked, and all overclocking is dependent on multipliers. You can overclock the CPU (if it's unlocked) while having zero effect on the RAM, and you can overclock the RAM with zero effect on the CPU.

You might want to consider the AMD APUs in this case. You would want someone else to confirm that they can handle 2000MHz+.

Click to expand...

SB memory controller is much faster than any AMD and can make really good results@1866. There are still available Dominators 2000 C8 or anything on PSC or Elpida 2000+ that should make 2000-2100 cl8 or 2133-2200 cl9 ( but not in 4GB sticks, maybe except 2-3 new kits that are really expensive ). On SB higher cpu clock = faster memory no matter if you change bclk or only cpu multi. On AMD higher cpu clock almost won't affect max memory bandwidth or access times ( there are only little changes in cache ) and almost all base on CPU-NB that is limited to about 18-20GB/s ( after higher oc ). High memory clock doesn't mean high memory performance.

If I'm right then all P67/Z68 boards have 2133 multi and then best idea would be to get something like 2133 CL9-11-9 that can run on cheaper cpus.

Components ordered

I finally ended up with the following components for my Varnish cache box. The RAM is PC15000 @1866MHz. However, the MB supports overclocking to 2400MHz. This combination should bring me 0.00000375 cycles at CAS9. I wrote an article further explaining my choices on my blog.http://nwlinux.com/thinking-memory-building-varnish-cache-server-part1/

Motherboard can OC that high, but it's probably too much of an OC on the memory. You're more memory limited on OCs then motherboard. It's better to get a higher speed kit of memory.