I have read that you can mix 55xx and 56xx. I think it is worth doing.

Your question is a good one but it is a bit complex. Perhaps, the question might be posed in two other questions, first, whether different processors can be "mixed" on the SR-2 motherboard and, second, how would the mixed processors impact performance?

The previous post answered the first question. You can mix CPUs provided they come from the same family. For example, you can install two Westmere processors and (my guess is that) the system would run. But -- because the two processors are interconnected --you cannot install a Westmere 56xx with a Nahelem 55xx processor . The two processors have differences in architecture.

The second question concerns how performance would be impacted. Here, my guess is that the interconnect speed and DDR3 type could be affected.  For example, suppose you chose two processors from the Westmere family, but one from the E56xx and the other from X56xx series. The E56xx processors have a QPI speed of 5.86 GT/s whereas the X56xx processors have a QPI speed of 6.4 GT/s. Similarly, suppose you chose two Westmere E-series processors but the processors supported different memory speeds. For example, the quad-core E5620 processor supports up to DDR3-1066 whereas the hexacore E5645 supports up to DDR3-1333. Such combination of processors raises the question how would the system run when the two processors that have different performance specs? My guess is that the mixed CPU system will always run at the lower performance (QPI or DDR3) level.
 
If memory speed -- in addition to capacity-- is critical to your application, I would choose two CPUs that support the same DDR3 performance, either DDR3-1066 or -1333 . If your application can run fine with 5.86 GT/s and DDR3-1066, I would choose the hexacore E5645 (instead of X5650) with the quad-core E5620 processor. But if your application requires uncompromising QPI and memory speed, I would bite the bullet and install two X56xx processors.

Way back when Shimano stated that CPUs must be paired from the same core family (Westmere with Westmere, Nehalem-EP with Nehalem-EP) But performance will scale correctly. Just get a E5620 and you should be good to go.
 
(edit: didn't read the professors whole block of text, consider this the short version.)

Just wondering if anyone used the E5620 and E5645 combo with the SR2 with any success?
How did they work together OC wise?
I have one of each and was thinking about getting the SR2 to use with them.
I know this is a old thread but thought it might be the best place to ask instead of starting a new one.
 
Thanks for your help...

Ya I gather that much but was looking for answers from someone that has actually used the two with the SR2.
I have a few other questions I would like to ask if someone has used this setup and can give some feed back on there findings.
Thanks
 
EDit: both my chips do right at 4.2Ghz with low vcore, so I hoping I can do the same with each on the SR2 or pretty close.
 
Not looking forward to dropping 550 bucks on something that can't get me there.

I'm sure they may have and I haven't looked up the specs on those two chips but I'm pretty sure there a different bread of horse then the two chips I have.
 
I already know I will most like have to use the lower memory setting to accommodate the E5620. 
 
Kind of already knew this since I been OCing for quite sometime.
Thanks to RetiredProfessor post it pretty much confirmed what I was already thinking.
 
For example, the quad-core E5620 processor supports up to DDR3-1066 whereas the hexacore E5645 supports up to DDR3-1333. Such combination of processors raises the question how would the system run when the two processors that have different performance specs? My guess is that the mixed CPU system will always run at the lower performance (QPI or DDR3) level.

Yes both chips have the same multipliers, basically there the same chips except the memory controller and one has 4 core where as the other is 6 cores.  Max usable muti is 21x unless you drop some cores then 22x or 22 turbo.
 
Edit sorry my bad on the multipliers 19x 20x turbo.
I run them at 19x221 witch comes out at 4195Mhz E5620 1.275v E5645 1.295v in
the two motherboards there running in right now.
Ya I know 19x221 doesn't come out right, but its my max BIOS with the boards and the BCLK droops a little at those settings.

sbinh

new2019

you can install any x5XXX series processor in Sr2 , it doesnt need to be identical , .

Not my case. I ran 2 x5650 but they are different stepping. One is A0, the another is B1. Couldn't boot up.
When ran each individually, worked fine .. boot right into windows.

Good info something I hadn't thought about. I'll have to check the stepping of each of my chips.
 
Thanks...
 
Still hoping to see some post from some that have ran a E5620 & a E5645 together and how it worked out for them.

CPUZ E5645 link doesn't work correctly. It shows result from E5620.

Oh .. I saw it now :D .. Sorry my bad.
Sell your E5620 and buy another E5645 ... :D ... or
Nice overclock though. How could you manage to run them at that speed with low vcore  ? Are those speed rock stable?

I'm now wondering if maybe I should have started a topic on E5620 & E5645 use in a SR2.
Maybe then I would get more responses for users of this combo?

sbinh

Don't know if it works, but I might try to mix/match x5650 (a0) with l5640 (a0) ... At least I can utilize my sr-2 board .. :D

Ya lets us know if you do and how it turns out.
On another note unless I already had a L5640 to try I wouldn't buy it over the X5650 since its only about $5 difference in price.
Multiplier wise you'd be better off with another X5650.