gregdnicolas :
some body :
what about with the window panel its says 168mm but the r1 is 168.3mm
It fits. I have an R1 Ultimate in my Define C (windowed version) but your ram should be low profile. I'm using a corsair lpx.
I understand this thread is pretty old, but did you have to make any adjustments to make the R1 Ultimate fit in the Define C w/ window? I was also planning on getting Corsair LPX as well. I just wanted to make sure because the measurements seem extremely tight with only a 0.3 cm larger size of the CPU cooler!