By my understanding you want to compare results of peig function using default values of nwin and noverlap. So you can find the sample example hope it will help:
fs = 100;
t = 0:1/fs:1-1/fs;
s = 2*sin(2*pi*25*t)+sin(2*pi*35*t)+randn(1,100);
X = corrmtx(s,12,'mod');
figure(1)
peig(X,2,512,fs) % default values of nwin = p(1) = 2 and noverlap = nwin-1.
figure(2)
peig(X,2,512,fs,20,10); % specifying nwin = 20, noverlap = 10.
For your case you can specify nwin = 6000 and noverlap = 3000.
