LINK to Intel FXX750GERPS compatible products. ALL those systems have something in common. They are in
R2000IP server system family (emphasis on IP).
Lets go a step further now. They all use an Intel
S2600IP server board, which work only in the Intel Server System Family
R2000IP or P4000IP. You can see this by looking the S2600IP compatible products
HERE. From that I can conclude that the chassis used in the IP family are different, specifically in the PSU and distribution boards, then other P4000 and R2000 servers. The motherboard PDF shows compatibility as follows;
R2000IP
FXX750GERPS PSU
FBF750PDB (power distribution board)
P4000IP
FXX750PCRPS: 750W Gold
FXX1200PCRPS: 1200 Platinum
PXX1600PCRPS: 1600 Platinum
FUPPDBHC: power distribution board (high current) for FXX750PCRPS, FXX1200PCRPS, or PXX1600PCRPS
FUPCRPSCAGE: CRPS PSU cage assembly
Note that even though the S2600IP BOARD is compatible with a P4000IP server family, it doesn't list the ERPS PSU, ONLY the R2000IP server family does!
Now go look up the P4000 chassis manual
HERE. Page 5 shows you what P4000 chassis models work with what motherboards. From that you can see the P4000L chassis is the only one that works with the SC2600IP. Other P4000 chassis end in S/M/L-WS and work with all different server boards. In the spare parts you can see the whole list of power parts.
FUP365SNRPS: 365W Silver (looks like standard ATX)
FUP550SNRPS: 550W Silver (looks like standard ATX)
FXX460GCRPS: 460W Gold
FXX750PCRPS: 750W Flatinum
FXX1200PCRPS: 1200 Platinum
PXX1600PCRPS: 1600 Platinum
FUPPDBLC: power distribution board (low current) for FXX460GCRPS or FXX750PCRPS
FUPPDBHC: power distribution board (high current) for FXX750PCRPS, FXX1200PCRPS, or PXX1600PCRPS
FUPCRPSCAGE: CRPS PSU cage assembly
Might want to note that the FXX750PCRPS PSU actually works on either power distribution board.
So what can I conclude from all this? I'm going to guess your system is (or at one point was) an R2000
IP. Perhaps you could take pictures because the PSU slot length/height should be obviously different. The FXX750GERPS is meant to be used in a R2000IP system containing an S2600IP board and wired to a FBF750PDB distribution board. It is NOT to be used in ANY P4000 system, even the P4000IP with an S2600IP board. And I suspect it will not even fit in other R2000 (non-IP system) chassis, at least not without some change in parts. So yes, The R2000 chassis have different power setups.
It would be nice to have a R2000 chassis compatibility manual like the P4000 one, but I don't see it anywhere.
EDIT: the reason I say it should be obvious about the chassis is because the R2000IP systems with the ERPS PSU's look like
THIS (2 x 1U stacked PSU's and long). If it is outfitted for a CRPS power supply it looks completely different. And looking at the R2000 chassis I have with CRPS PSU's, I don't see how you would even be able to swap it over to take the ERPS PSU's with the way the back of the server is built (it's part of the chassis in that area).